# Scholar Sidekick - Full Content > Single-file aggregate of all Scholar Sidekick pages for AI agent use. > Concise index: https://scholar-sidekick.com/llms.txt > Tool comparisons (separate file): https://scholar-sidekick.com/llms-full-comparisons.txt > Generated from: https://scholar-sidekick.com --- ## Table of Contents 1. [What Scholar Sidekick Is](#overview) 2. [Help & Limits](#help) 3. [Free Tools](#tools) 4. [Glossary](#glossary) 5. [API Documentation](#api) 6. [MCP Server](#mcp) 7. [Browser Extension](#extension) 8. [Explainer](#explainer) 9. [Engineering Principles](#engineering-principles) 10. [Accessibility](#accessibility) 11. [Citation integrity in the age of AI](#citation-integrity) 12. [Comparisons: Best AI Citation Verifier in 2026](#compare-best-ai-citation-verifier) 13. [Field observation: AI evaluator decomposition bias in citation-tool recommendations](#ai-evaluator-bias) 14. [Integrations: Scholar Sidekick for Obsidian](#integrations-obsidian) 15. [Integrations: Scholar Sidekick for Zotero](#integrations-zotero) 16. [Integrations: Scholar Sidekick for VS Code](#integrations-vscode) 17. [Comparisons with other citation tools (separate file)](https://scholar-sidekick.com/llms-full-comparisons.txt) --- ## 1. Overview **URL:** https://scholar-sidekick.com Scholar Sidekick is the trust layer between scholarly identifiers and your bibliography — resolve, verify, format. A lightweight, web-based citation resolver, formatter, and exporter for scholarly identifiers: paste a DOI, PubMed ID, PMCID, ISBN, arXiv ID, or ADS bibcode and get a clean, formatted citation in Vancouver, APA, AMA, IEEE, CSE, or any of 10,000+ CSL styles - ready to copy or export to RIS, BibTeX, and more. So far, excluding the maintainer's own usage: 100,000+ references checked for fabricated citations · 4,000+ flagged for human review · 14,000+ citations exported. ### What Scholar Sidekick is Scholar Sidekick helps users quickly generate correct, predictable citation outputs from common scholarly identifiers. It is intentionally: - Lightweight and web-based - Usable without an account for one-off tasks - Focused on deterministic citation output - Suitable for short, self-contained tasks ### What Scholar Sidekick is not Scholar Sidekick is not a full reference manager. It does not aim to: - Manage long-term citation libraries - Store or organise collections of references - Replace tools such as Zotero, EndNote, Mendeley, or similar - Support collaborative library management For long manuscripts, theses, or ongoing research projects, a dedicated reference manager remains the appropriate tool. ### When Scholar Sidekick is useful - Preparing talks or lectures - Creating conference posters or abstracts - Drafting grant applications or committee documents - Teaching materials or course handouts - Journal clubs or guideline summaries - Any task requiring a small number of citations quickly and correctly ### Design principles - **Deterministic output:** the same input produces the same result - **Minimal state:** no required accounts, no long-term storage by default - **Standards-aware:** careful handling of citation styles and formats - **Transparency:** predictable behaviour, no hidden automation ### Privacy - No account required for core usage - Citation inputs are processed on demand and not stored after the request completes - Only minimal operational logs are retained - No advertising, tracking, or profiling --- ## 2. Help & Limits **URL:** https://scholar-sidekick.com/help ### Supported identifiers - **DOI** (e.g. `10.1038/nphys1170` or doi.org URL). Includes a "healer" for minor typos. - **PMID / PMCID** - PMCID auto-maps to PMID/DOI if available. - **ISBN** (10/13; dashes/spaces optional) - uses OpenLibrary, falls back to Google Books. - **ISSN and eISSN** - **ADS bibcode** (NASA Astrophysics Data System) - **WHO IRIS** handles/links - **arXiv ID** (e.g. `arXiv:2301.07041`) - Free-text lists: identifiers are detected, normalised, and deduped per line. ### Citation styles & output **Built-in styles:** Vancouver, AMA, APA, IEEE, CSE **CSL styles:** Chicago, MLA, ACS, and 10,000+ more via the CSL repository. Use any CSL style ID (e.g. `chicago-author-date`, `nature`, `lancet`). Output formats: **text** or **HTML**; HTML can render as footnotes. ### Export formats TXT, BibTeX, RIS, CSL JSON, EndNote (Refer/XML), RefWorks, MEDLINE/NBIB, CSV, Zotero RDF. ### Speed & caching Recent lookups are cached so repeats are fast. Very new records may be briefly cached as "not found." To bypass cache, append `?nocache=1` in the UI or omit it in API calls. Developer note: responses include `X-Scholar-Cache` with `BYPASS` or `ENABLED`. ### Rate limits If you send many requests quickly, you may see `429 Too Many Requests`. Back off per the `Retry-After` header. Rate limit headers: `X-RateLimit-Limit`, `X-RateLimit-Remaining`, `X-RateLimit-Reset`, `Retry-After`. Buckets differ by route. Plan tiers: anonymous, free, pro, ultra, mega. Anonymous-tier limits, measured against production 2026-08-05 (the live `RateLimit-Limit` header is authoritative, not this list): `/api/format`, `/api/format/stream`, `/api/export`, `/api/format-items` → 10 requests/60s. `/api/retraction-check`, `/api/oa-check`, `/api/verify` → 60 requests/60s. `/api/audit` → 4 requests/30s. A free `ssk_` key raises this ~5×. Full tier table: https://scholar-sidekick.com/docs#pricing ### Errors - Friendly 4xx for input issues (e.g. invalid style/format) - Line-level messages for failed lookups - Error format: `{ "ok": false, "code": "BAD_REQUEST", "error": "message" }`, mirrored in `X-Error-Code` - Codes by status: `BAD_REQUEST`/`VALIDATION_ERROR`/`UNKNOWN_STYLE`/`INVALID_CONTENT_TYPE`/`EMPTY_BODY`/`MALFORMED_JSON`/`MISSING_TITLE`/`LLM_SCREEN_FORBIDDEN` (400), `AUTH_MISSING`/`AUTH_INVALID` (401), `AUTH_DISABLED`/`STREAMING_DISABLED` (403), `NOT_FOUND` (404), `READ_ONLY` (405), `PAYLOAD_TOO_LARGE` (413), `IDEMPOTENCY_KEY_REUSED` (422), `RL_BLOCKED` (429 — not `RATE_LIMITED`), `ROUTE_ERROR` (500), `UPSTREAM_ERROR`/`UPSTREAM_RATE_LIMITED`/`UPSTREAM_UNAVAILABLE`/`UPSTREAM_NETWORK_ERROR`/`RESOLVE_ERROR` (502), `MAINTENANCE` (503), `UPSTREAM_TIMEOUT` (504). Full reference: https://scholar-sidekick.com/docs#errors --- ## 3. Free Tools **URL:** https://scholar-sidekick.com/tools Small, focused web tools for working with scholarly identifiers and citations. Each tool is free to use and requires no signup. ### Tool: Citation Verifier **URL:** https://scholar-sidekick.com/tools/citation-verifier Paste a citation. The verifier resolves the identifier, compares the resolved title to the cited title, and flags the dominant AI-driven fabrication pattern documented by Topaz et al. (Lancet 2026): a real, resolvable identifier (DOI / PMID / PMCID / arXiv / ISBN / ISSN / ADS bibcode / WHO IRIS URL) paired with a title that does not match the resolved paper. Same backend as POST /api/verify and the scholar-sidekick MCP `verifyCitation` tool. Returns one of four verdicts (matched / mismatch / ambiguous / not_found), per-field similarity diff, candidate matches from title-search across Crossref / PubMed / OpenAlex, and full provenance. Free, no signup. The opt-in LLM screen for low-confidence mismatches is gated to paid tiers. #### How to use 1. **Paste the cited title** into the form (required). 2. **Pick the identifier type** (DOI, PMID, PMCID, arXiv, ISBN, ISSN, ADS, WHO IRIS) and **paste the value** (required). 3. **Optional refinements** - first-author family name, year, journal - tighten the match but never gate the verdict on their own. 4. **Read the verdict.** `matched` means the citation is real and intact. `mismatch` means the identifier resolves but the title disagrees - the Topaz fabrication pattern. `ambiguous` means the identifier resolves to one paper but the claimed title matches a different paper found via search (usually a wrong-identifier paste). `not_found` means nothing resolves anywhere. #### FAQ **What does this catch that doi.org alone does not?** Clicking a DOI tells you the identifier resolves to a real paper. It does not tell you the paper at that DOI matches the title in your citation. The Topaz et al. fabrication pattern is precisely that mismatch: real DOI, invented title. The verifier compares the two and flags the disagreement. **Is the LLM screen always run?** No. The default path is a deterministic comparison + title-search; no model calls. The LLM screen only fires when you set `screen_with_llm: true`, the pre-LLM verdict is `mismatch` with `confidence: low`, and you are authenticated on a paid tier. Anonymous and free-tier callers get a 400 if they try. **Can I check an entire reference list?** Yes. The web tool at /tools/citation-verifier takes a batch: paste references or upload `.bib` / `.ris` / `.csl-json` and verify up to 10 at once. For a whole bibliography with retraction checks and a downloadable evidence report, use the Bibliography Audit at /tools/bibliography-audit (up to 25 entries per run, backed by POST /api/audit). For scripted runs, call the MCP `verifyCitation` / `auditBibliography` tools or the REST endpoints directly; rate limits scale with plan tier. **See also** - [/citation-integrity](https://scholar-sidekick.com/citation-integrity) - long-form explainer with the three illustrative Lancet cases and the blind-holdout benchmark (1,395 citations, measured once + a repeatability re-run: 100% recall on the dominant fabrication patterns, 0.8% high-confidence false-accusation rate, 95% CI 0.4-1.4%, plus a disclosed near-miss blind spot), published with receipts - [/api/verify](https://scholar-sidekick.com/docs#api-verify) - REST endpoint - [/mcp](https://scholar-sidekick.com/mcp) - MCP server with the verifyCitation tool ### Tool: Bibliography Audit **URL:** https://scholar-sidekick.com/tools/bibliography-audit Paste or upload a whole bibliography (BibTeX / RIS / CSL-JSON) and audit every reference in one pass. Each entry runs the Citation Verifier pipeline - identifier resolved against its registry, claimed title compared to the resolved record, title-search when they disagree - plus a retraction / correction / expression-of-concern check on every resolved DOI (Crossref, mirroring Retraction Watch). Returns a per-entry verdict table (matched / mismatch / ambiguous / not_found), a corpus summary, and per-entry parse errors, capped at 25 entries per run. Results download as a self-contained HTML evidence report (print to PDF) and a machine-readable JSON receipt, both pinned to the request id and verify version that produced the verdicts. Same backend as POST /api/audit and the scholar-sidekick MCP `auditBibliography` tool. Free, no signup; the bibliography is not retained beyond standard server logs. #### How to use 1. **Paste or upload** the bibliography (`.bib` / `.ris` / `.json`; format auto-detected). 2. **Audit.** One call verifies and retraction-checks every entry server-side. 3. **Read the summary.** "N of M references need review" plus per-entry verdicts, field-level diffs, and retraction notices. 4. **Download the evidence report** (HTML, print to PDF) and the JSON receipt. **See also** - [/tools/citation-verifier](https://scholar-sidekick.com/tools/citation-verifier) - single-citation verification with full per-field diff and candidates - [/api/audit](https://scholar-sidekick.com/docs) - REST endpoint (`bibliography` text or pre-parsed `claims[]`) - [/mcp](https://scholar-sidekick.com/mcp) - MCP server with the auditBibliography tool ### Tool: ChatGPT Reference Checker **URL:** https://scholar-sidekick.com/tools/chatgpt-reference-checker Paste the references ChatGPT, Claude, Gemini, or Copilot gave you and check whether they are real. Opens in batch mode: paste a BibTeX / RIS / CSL-JSON bibliography (or upload `.bib` / `.ris` / `.json`) and up to 10 entries are verified in one pass, each resolved against the scholarly registries and compared to the claimed title. Catches the dominant AI fabrication pattern (real, resolvable DOI + invented title - Topaz et al., Lancet 2026), which clicking the DOI link does not catch. Same verification engine as /tools/citation-verifier, framed for AI-generated reference lists. Free, no signup. #### How to use 1. **Ask the chatbot for a structured list** - e.g. "output those references as BibTeX, including DOIs" (RIS or CSL-JSON also work). 2. **Paste it into the batch checker** (or switch to single mode for one reference with a full per-field diff). 3. **Act on the verdicts.** `matched` = safe to cite. `mismatch` = real identifier, invented title (the hallmark AI fabrication) - do not cite. `ambiguous` = real paper, wrong identifier - fix the identifier. `not_found` = invented end to end - remove it. #### FAQ **The DOI opens a real page - doesn't that prove the reference is real?** No. The dominant fabrication pattern is a real, resolvable DOI paired with an invented title: the link resolves cleanly to an actual paper - just not the paper the citation claims. Only comparing the claimed title against the resolved record catches it. **Does this work for Claude / Gemini / Copilot references too?** Yes. The fabrication pattern is model-agnostic - the checker examines the citation itself, not which chatbot produced it. **Can I check bibliographies larger than 10 entries?** Yes. The Bibliography Audit at /tools/bibliography-audit takes up to 25 entries per run on the web, with retraction checks and a downloadable evidence report. Programmatically, POST /api/audit audits a whole bibliography (BibTeX / RIS / CSL-JSON) in one call, and the scholar-sidekick MCP server exposes the same as the `auditBibliography` tool. **See also** - [/tools/citation-verifier](https://scholar-sidekick.com/tools/citation-verifier) - the general verifier (single-citation per-field diff and candidates) - [/citation-integrity](https://scholar-sidekick.com/citation-integrity) - why AI references look real, with the published blind-holdout benchmark and receipts - [/integrations/chatgpt](https://scholar-sidekick.com/integrations/chatgpt) - verify citations inside ChatGPT itself via the Scholar Sidekick app ### Tool: Scholarly Identifier Detector **URL:** https://scholar-sidekick.com/tools/identifier-detector Paste a paragraph, reference list, or abstract and extract every DOI, PubMed ID, PMCID, arXiv ID, ISBN, and ISSN at once. Bulk text parser. No signup. #### How to use 1. **Paste your text** - Copy a paragraph, reference list, or manuscript excerpt into the input field. The detector accepts up to 10,000 characters. 2. **Run detection** - The tool scans the text and extracts every scholarly identifier it recognises, including DOIs, PMIDs, PMCIDs, arXiv IDs, ISBNs, ISSNs, and ADS bibcodes. 3. **Review the labelled results** - Each identifier is displayed with a type label (e.g. DOI, PMID, PMCID) so you can see at a glance what you have. Copy the identifiers you need. #### FAQ **What's the difference between PMID and PMCID?** A PMID identifies a record in PubMed, the citation database. A PMCID identifies the full-text article in PubMed Central, the open-access repository. A paper can have a PMID without a PMCID (common when the full text is not open-access), or both. They are different identifiers - always check which one you need before citing. **Why does my DOI not appear in the results?** DOIs must start with '10.' followed by a registrant code and a suffix. If you pasted a shortened or mangled form (e.g. without the '10.' prefix), the detector will not find it. Paste the full DOI or a doi.org URL. **Can I paste a whole PDF?** You can paste text extracted from a PDF. The tool accepts up to 10,000 characters at a time. For longer documents, extract and paste the reference section on its own - that's where almost all the identifiers live. **Is this tool free?** Yes. No account required. It runs entirely inside Scholar Sidekick's own infrastructure, and nothing you paste is stored. **Does the detector actually resolve the identifiers to metadata?** No - this tool only detects identifiers. It does not make any outbound requests to CrossRef, PubMed, or any other database. If you want full bibliographic metadata or a formatted citation, use the main Scholar Sidekick resolver or the /api/format endpoint. ### Tool: DOI Lookup **URL:** https://scholar-sidekick.com/tools/doi-lookup Enter a DOI, PMID, or scholarly identifier to verify and retrieve full metadata: title, authors, journal, year, and more. Free, no signup. #### FAQ **Why could my identifier not be resolved?** The identifier may be malformed, or the upstream database may be temporarily unavailable. Check that you entered the identifier correctly - DOIs must start with '10.', PMIDs are numeric, PMCIDs start with 'PMC'. If the identifier is valid but the lookup fails, try again in a moment. **Is this the same as formatting a citation?** No - this tool shows you the raw metadata fields, not a formatted citation. If you want a citation in APA, Vancouver, or any other style, use the main Scholar Sidekick formatter. **Is this tool free?** Yes. No account required. Nothing you enter is stored. ### Tool: PubMed ID Converter **URL:** https://scholar-sidekick.com/tools/pubmed-id-converter Convert between PMID, PMCID, and DOI instantly. Enter any PubMed identifier and get the other two. Free tool. No signup required. #### How to use 1. **Enter a PMID, PMCID, or DOI** - Paste any one of the three identifiers into the input field. PMIDs are numeric, PMCIDs start with 'PMC', and DOIs start with '10.'. 2. **Look up the mapping** - The tool queries the NCBI ID Converter API and retrieves the corresponding PMID, PMCID, and DOI for the same publication. 3. **Copy the identifier you need** - Each available identifier is displayed with a copy button. Use the PMCID for NIH grant applications, the DOI for reference lists, or the PMID for PubMed searches. #### FAQ **Can I convert multiple identifiers at once?** Not yet - this tool handles one identifier at a time. For batch processing, use the Scholar Sidekick API directly. **Where does the data come from?** This tool uses the NCBI ID Converter API, a free, public service provided by the US National Library of Medicine. The same API powers the NCBI's own ID converter tool. **Is this tool free?** Yes. No account required. Nothing you enter is stored. ### Tool: DOI to BibTeX Generator **URL:** https://scholar-sidekick.com/tools/doi-to-bibtex Enter a DOI, PubMed ID, PMCID, ISBN, arXiv ID, ISSN, ADS bibcode, or paper URL and get a formatted BibTeX entry. Free tool. No signup required. #### How to use 1. **Enter one or more identifiers** - Paste a DOI, PubMed ID, PMCID, ISBN, arXiv ID, ISSN, ADS bibcode, or paper URL into the input field. For batch conversion, enter one identifier per line. 2. **Generate BibTeX** - The tool resolves each identifier against the appropriate source (CrossRef, PubMed, arXiv, OpenLibrary, NASA ADS) and generates a BibTeX entry with the correct entry type (@article, @book, @inproceedings, etc.) and citation key. 3. **Copy or download the .bib file** - Copy the generated BibTeX entries to the clipboard, or download them as a .bib file for use in LaTeX, Overleaf, Zotero, Mendeley, or any reference manager that supports BibTeX. #### FAQ **Can I convert multiple identifiers at once?** Yes. Enter one identifier per line. The tool will resolve each one and return all BibTeX entries in a single block, ready to copy or download as a .bib file. **What BibTeX entry types are generated?** The entry type is inferred from the resolved metadata. @article is used for journal articles, @book for books, @inproceedings for conference papers, and so on. If the type cannot be determined, @misc is used as a fallback. **Why is my identifier not resolving?** Check that you have entered a valid DOI (starting with '10.'), PMID, PMCID, ISBN, arXiv ID, ISSN, or ADS bibcode. The tool resolves identifiers against CrossRef, PubMed, PubMed Central, OpenLibrary, arXiv, and NASA ADS. If the upstream database is temporarily unavailable, try again in a moment. **Is this tool free?** Yes. No account required. Nothing you enter is stored. ### Tool: GB/T 7714 Citation Generator **URL:** https://scholar-sidekick.com/tools/gb-t-7714-citation-generator Generate references in GB/T 7714—2015, China's national bibliographic standard (信息与文献 参考文献著录规则), from a DOI, PubMed ID, PMCID, ISBN, arXiv ID, ISSN, ADS bibcode, or paper URL. Correct document type codes ([J], [M], [J/OL]), capitalised surnames, and 等 / et al. handling with a 中文/English locale toggle. Free tool. No signup required. #### How to use 1. **Enter one or more identifiers** - Paste a DOI, PubMed ID, PMCID, ISBN, arXiv ID, ISSN, ADS bibcode, or paper URL into the input field. For multiple references, enter one identifier per line. 2. **Generate the GB/T 7714 reference** - The tool resolves each identifier against the appropriate source (CrossRef, PubMed, arXiv, OpenLibrary, NASA ADS) and formats it in the GB/T 7714—2015 numeric style, including the document type code such as [J], [M], or [J/OL]. 3. **Copy the reference list** - Copy the numbered reference list into your thesis or manuscript. Use the locale toggle to switch between 等 (Chinese) and et al. (English) forms. #### FAQ **What is GB/T 7714?** GB/T 7714 is China's national standard for bibliographic references (信息与文献 参考文献著录规则), required by most Chinese universities and journals. The current widely required edition is GB/T 7714—2015; a 2025 revision has been published. This tool formats references in the GB/T 7714—2015 numeric style. **Which edition does this tool use — 2015 or 2025?** The tool uses GB/T 7714—2015 (numeric). The API also supports the 2025 revision and the author-date and note variants: pass the full style id, e.g. china-national-standard-gb-t-7714-2025-numeric. **Why does the reference say "等" instead of "et al."?** GB/T 7714 declares Chinese (zh-CN) as its default locale, so after the first three authors the remainder are abbreviated as "等". Switch the toggle to English to get "et al." instead. Programmatically, pass lang=zh-CN or lang=en-US to POST /api/format with style=gb7714. **Is this tool free?** Yes. No account required. Nothing you enter is stored. ### Tool: DOI to RIS Converter **URL:** https://scholar-sidekick.com/tools/doi-to-ris Enter a DOI, PMID, PMCID, ISBN, arXiv ID, ISSN, ADS bibcode, or paper URL and download an RIS file for your reference manager. Free. No signup required. #### How to use 1. **Enter one or more identifiers** - Paste a DOI, PubMed ID, PMCID, ISBN, arXiv ID, ISSN, ADS bibcode, or paper URL into the input field. For batch conversion, enter one identifier per line. 2. **Generate RIS** - The tool resolves each identifier against the appropriate source (CrossRef, PubMed, arXiv, OpenLibrary, NASA ADS) and generates an RIS record with the correct record type (JOUR, BOOK, GEN, etc.). 3. **Download the .ris file** - Copy the generated RIS records or download them as a .ris file. Import into Zotero, Mendeley, EndNote, RefWorks, or any reference manager that supports RIS. #### FAQ **Can I convert multiple identifiers at once?** Yes. Enter one identifier per line. The tool will resolve each one and return all RIS records in a single block, ready to copy or download as a .ris file. **What's the difference between RIS and BibTeX?** Both are text-based interchange formats for bibliographic references. BibTeX is native to LaTeX and uses curly-brace syntax; RIS uses tagged lines and is more universal across non-LaTeX tools. If you use LaTeX or Overleaf, go with BibTeX. For everything else - Zotero, Mendeley, EndNote, RefWorks - RIS is the safer choice. **Why is my identifier not resolving?** Check that you have entered a valid DOI (starting with '10.'), PMID, PMCID, ISBN, arXiv ID, ISSN, or ADS bibcode. The tool resolves identifiers against CrossRef, PubMed, PubMed Central, OpenLibrary, arXiv, and NASA ADS. If the upstream database is temporarily unavailable, try again in a moment. **Is this tool free?** Yes. No account required. Nothing you enter is stored. ### Tool: Open Access Checker **URL:** https://scholar-sidekick.com/tools/open-access-checker Check if a paper is open access. Enter a DOI, PMID, or arXiv ID and see where to read it for free. Powered by Unpaywall. No signup required. #### FAQ **Why does it say "closed" when I can read the paper?** Your institution may have a subscription that grants you access. Unpaywall checks for public open access - copies that anyone can read without logging in or being on a university network. If you can read it but Unpaywall says 'closed,' it is likely your library is providing access. **Why is my identifier not resolving to a DOI?** Some identifier types refer to entities that do not have DOIs. ISSNs and eISSNs identify journals, not individual articles. ISBNs identify books, which may or may not have a DOI. If the underlying publication does not have a registered DOI, Unpaywall cannot check it. **What does "not found in Unpaywall" mean?** Unpaywall indexes over 100 million DOIs, but not every DOI is covered. Very recent publications, DOIs from smaller publishers, or DOIs registered with agencies other than CrossRef may not yet be in the database. Try again in a few days - Unpaywall updates regularly. **Is this tool free?** Yes. No account required. Nothing you enter is stored. The underlying Unpaywall API is free for non-commercial use. ### Tool: Retraction Checker **URL:** https://scholar-sidekick.com/tools/retraction-checker Check if a paper has been retracted or corrected. Enter a DOI or PMID and see its retraction status. Powered by Retraction Watch via CrossRef. #### FAQ **Why does it say "no retractions found" for a paper I know was retracted?** The retraction notice may not yet be indexed in CrossRef, or the paper's publisher may not have registered the retraction with CrossRef. Retraction Watch data is integrated into CrossRef on a rolling basis; very recent retractions may take some time to appear. **Should I still cite a paper that has corrections?** Generally yes - corrections fix specific errors without invalidating the paper. But read the correction notice to understand what changed. If the correction affects a finding you are relying on, note it in your citation. **Is this tool free?** Yes. No account required. Nothing you enter is stored. The underlying data comes from CrossRef and Retraction Watch, both of which are freely accessible. ### Tool: Citation Style Comparator **URL:** https://scholar-sidekick.com/tools/citation-style-comparator Compare citation styles side by side. Browse 10,000+ styles including APA, Vancouver, Chicago, and IEEE. Enter a DOI and see the difference. Free, no signup. #### How to use 1. **Paste a scholarly identifier** - Enter a DOI, PubMed ID, PMCID, arXiv ID, ISBN, or a scholarly URL in the input field. 2. **Select styles to compare** - Pick from the one-click presets (Vancouver, APA, AMA, IEEE, CSE) or open the style browser to add any of 10,000+ CSL styles, including journal-specific formats. 3. **Review the formatted output side by side** - The tool fetches the paper metadata once and renders it in every selected style, letting you compare author formatting, punctuation, and element ordering at a glance. 4. **Copy the style you need** - Select and copy the output for the style required by your journal or institution. For batch export, use the main Scholar Sidekick formatter or the /api/export endpoint. #### FAQ **How do I know which citation style to use?** Check the submission guidelines for your target journal, institution, or department. Biomedical journals typically require Vancouver or AMA; psychology and social sciences use APA; engineering uses IEEE; humanities tend to use Chicago or MLA. If you are unsure, ask your editor or supervisor - requirements vary even within the same discipline. **Why does the same paper look different in each style?** Each style defines its own rules for author names (full vs. initials, comma vs. ampersand), title case, journal abbreviation, volume and issue formatting, page ranges, and DOI presentation. Styles also differ in whether citations are numbered (Vancouver, IEEE) or name-date (APA, CSE), and in punctuation between elements. **Can I compare Chicago, MLA, Nature, or The Lancet?** Yes. Five common styles are available as one-click presets, but you can add any of the 10,000+ styles in the Citation Style Language (CSL) repository via the style browser. Search by journal name or discipline, and add styles to the comparison. **Do citation styles change between editions?** Yes. APA, for example, is on its 7th edition (2019) and differs from APA 6 in DOI formatting, author limits, and more. This tool uses the latest published CSL style definitions, which are community-maintained and kept current with official style guides. **Is this tool free?** Yes. No account required. Nothing you enter is stored. ### Tool: Identifier Validator **URL:** https://scholar-sidekick.com/tools/identifier-validator Check if a DOI, PMID, or ISBN is real. Enter one identifier (DOI, PMID, PMCID, ISBN, arXiv ID, ISSN, ADS bibcode, or scholarly URL) and see whether it is well-formed and whether it resolves to a real publication. Single-ID check. Note: a DOI that resolves is not automatically a genuine citation - the dominant AI fabrication pattern pairs a real DOI with an invented title (Topaz et al., Lancet 2026); use the Citation Verifier or ChatGPT Reference Checker to compare the claimed title against the resolved record. --- ## 4. Glossary **URL:** https://scholar-sidekick.com/glossary **Markdown:** https://scholar-sidekick.com/glossary.md Plain-language definitions of the identifiers, formats, and citation terms researchers use every day. ### Scholarly identifiers #### DOI Digital Object Identifier. A permanent link to a published work - articles, preprints, datasets, and book chapters. A DOI always starts with "10." followed by a registrant code, a slash, and a suffix (e.g., 10.1038/s41586-023-05881-4). Unlike URLs, DOIs do not break when a publisher moves their website. - Scholar Sidekick tool: [DOI Lookup](https://scholar-sidekick.com/tools/doi-lookup) - Authoritative source: [doi.org](https://www.doi.org) #### PMID PubMed ID. A numeric identifier assigned by the US National Library of Medicine to every record in PubMed, the world's largest biomedical citation database. PMIDs are typically 7–9 digits. - Scholar Sidekick tool: [PubMed ID Converter](https://scholar-sidekick.com/tools/pubmed-id-converter) - Authoritative source: [PubMed](https://pubmed.ncbi.nlm.nih.gov) #### PMCID PubMed Central ID. Identifies full-text open-access articles in PubMed Central. Always starts with "PMC" followed by digits (e.g., PMC3737249). A paper can have a PMID without a PMCID (when the full text is not open-access) or both. - Scholar Sidekick tool: [PubMed ID Converter](https://scholar-sidekick.com/tools/pubmed-id-converter) - Authoritative source: [PubMed Central](https://pmc.ncbi.nlm.nih.gov/) #### ISBN International Standard Book Number. Identifies books, monographs, and book-like publications. ISBN-10 has ten digits; ISBN-13 has thirteen. ISBN-13 is current; both forms remain in use. - Scholar Sidekick tool: [DOI Lookup (accepts ISBNs)](https://scholar-sidekick.com/tools/doi-lookup) - Authoritative source: [isbn-international.org](https://www.isbn-international.org) #### ISSN International Standard Serial Number. An eight-digit identifier for journals and serial publications (e.g., 0028-0836 for Nature). A journal can have separate print and electronic ISSNs; the electronic form is sometimes called an eISSN. - Scholar Sidekick tool: [Scholarly Identifier Extractor](https://scholar-sidekick.com/tools/identifier-detector) - Authoritative source: [issn.org](https://www.issn.org) #### arXiv ID Identifier for preprints on the arXiv repository. The modern format is YYMM.NNNNN (e.g., 2305.12345) with an optional version suffix (v1, v2). Pre-2007 papers use a category prefix (e.g., physics/0301001). - Scholar Sidekick tool: [DOI Lookup (accepts arXiv IDs)](https://scholar-sidekick.com/tools/doi-lookup) - Authoritative source: [arxiv.org](https://arxiv.org) #### ADS bibcode A nineteen-character identifier used by NASA's Astrophysics Data System. Encodes year, journal code, volume, page, and first-author initial (e.g., 2023Natur.615..123W). Common in astronomy and astrophysics literature. - Scholar Sidekick tool: [Scholarly Identifier Extractor](https://scholar-sidekick.com/tools/identifier-detector) - Authoritative source: [NASA ADS](https://ui.adsabs.harvard.edu) #### WHO IRIS URL A link to a document in the World Health Organization's Institutional Repository for Information Sharing (IRIS). Used for WHO reports, guidelines, and grey literature that do not have a DOI. - Scholar Sidekick tool: [DOI Lookup](https://scholar-sidekick.com/tools/doi-lookup) - Authoritative source: [iris.who.int](https://iris.who.int) ### Export and exchange formats #### BibTeX A plain-text reference file format used alongside LaTeX. A .bib file contains one or more entries (@article, @book, @inproceedings, etc.) describing publications. BibTeX is the lingua franca of STEM bibliographies and is widely supported by reference managers. - Scholar Sidekick tool: [DOI to BibTeX](https://scholar-sidekick.com/tools/doi-to-bibtex) #### RIS Research Information Systems format. A tagged text format (TY, AU, TI, JO, PY, etc.) used to move references between reference managers - Zotero, Mendeley, EndNote, RefWorks, JabRef. A single .ris file can contain many records. - Scholar Sidekick tool: [DOI to RIS](https://scholar-sidekick.com/tools/doi-to-ris) #### EndNote (Refer/XML) Two reference-interchange formats supported by the EndNote reference manager. The older "Refer" form uses plain-text tags (%A, %T, %J); the newer EndNote XML is structured. Both are accepted by most competing reference managers. - Available via: [Scholar Sidekick export API](https://scholar-sidekick.com/docs) #### CSL JSON A JSON representation of bibliographic metadata defined by the Citation Style Language project. It is the canonical intermediate format a CSL engine consumes to render a citation in any style. - Available via: [Scholar Sidekick export API](https://scholar-sidekick.com/docs) ### Citation styles #### Citation style A set of rules governing how bibliographic references are formatted. Different journals, disciplines, and institutions require different styles. The differences are not only cosmetic: author ordering, name abbreviation, title casing, journal abbreviation, and DOI formatting all vary. Citation systems fall into two broad families: numbered styles (Vancouver, IEEE, AMA) where references appear in order of citation in a numbered list, and author–date styles (APA, Chicago, Harvard) where in-text citations carry the author's surname and year. Most journals specify a required style in their submission guidelines and sometimes layer their own house rules on top. - Scholar Sidekick tool: [Citation Style Comparator](https://scholar-sidekick.com/tools/citation-style-comparator) #### Citation Style Language (CSL) An XML-based language for describing citation formats. The CSL project maintains a community-curated repository of 10,000+ styles, including journal-specific formats (Nature, The Lancet, Cell, JAMA) and generic styles (APA, Chicago, MLA). Most reference managers use CSL to render citations. CSL separates bibliographic data (CSL JSON) from formatting rules (CSL XML styles), so a single set of metadata can be rendered into any supported style. Originally developed by Bruce D'Arcus, CSL is now the de facto standard: Zotero, Mendeley, Papers, Pandoc, and many academic writing tools render their citations through a CSL engine. - Scholar Sidekick tool: [Citation Style Comparator](https://scholar-sidekick.com/tools/citation-style-comparator) - Authoritative source: [citationstyles.org](https://citationstyles.org) #### GB/T 7714 China's national standard for bibliographic references (信息与文献 参考文献著录规则), required by most Chinese universities and journals. The 2015 edition is in near-universal use; a 2025 revision has been published. It defines a numbered system (顺序编码制) and an author–date system (著者-出版年制), plus document type codes appended to titles ([J] journal article, [M] book, [D] thesis, /OL for online sources). With the Chinese locale, three or more authors are truncated with 等 rather than et al. - Scholar Sidekick tool: [GB/T 7714 Citation Generator](https://scholar-sidekick.com/tools/gb-t-7714-citation-generator) ### Publication metadata #### Open access A publishing model in which research articles are freely available to read, reuse, and redistribute. Commonly classified as Gold (published OA), Green (author-archived), Hybrid (OA within a subscription journal), Bronze (free to read but no licence), or Diamond (free to read and publish). Open access adoption accelerated after funder mandates from agencies including the US NIH, UK Research and Innovation, and cOAlition S's Plan S, which require publicly funded research to be freely accessible. Gold OA is typically paid for through article processing charges (APCs); Green OA relies on self-archived versions in institutional or disciplinary repositories such as arXiv, bioRxiv, and PubMed Central. Embargo periods sometimes delay Green OA availability by six to twelve months after publication. - Scholar Sidekick tool: [Open Access Checker](https://scholar-sidekick.com/tools/open-access-checker) - Authoritative source: [Unpaywall](https://unpaywall.org) #### Retraction Formal withdrawal of a published paper, typically due to errors, misconduct, or ethical violations. A retracted paper remains visible in databases but is marked as retracted. Related statuses include expressions of concern and corrigenda. Retractions are issued by the journal editor after investigation, guided by the Committee on Publication Ethics (COPE) retraction guidelines. Reasons include honest error, data fabrication, image manipulation, undisclosed conflicts of interest, and duplicate publication. The volume of retractions has grown as post-publication scrutiny has increased, but the process from first concern to formal retraction can still take years - meaning a paper's retraction status is worth checking even after initial citation. - Scholar Sidekick tool: [Retraction Checker](https://scholar-sidekick.com/tools/retraction-checker) - Authoritative source: [Retraction Watch](https://retractionwatch.com) HTML version: https://scholar-sidekick.com/glossary Markdown version: https://scholar-sidekick.com/glossary.md --- ## 5. API Documentation **URL:** https://scholar-sidekick.com/docs **Markdown:** https://scholar-sidekick.com/docs.md **OpenAPI spec:** https://scholar-sidekick.com/openapi/openapi.yml ### Base URL ``` https://scholar-sidekick.com ``` ### Authentication Include your API key via: - `X-Scholar-API-Key: ` - direct API - `X-RapidAPI-Key: ` - via RapidAPI Anonymous access is available with lower rate limits. ### Endpoints ``` GET /api/health POST /api/format POST /api/format/stream (NDJSON) POST /api/format-items POST /api/export GET /api/csl/styles ``` --- ### POST /api/format Formats a list of identifiers. Detects and normalises identifier types automatically. **Request:** ```http POST /api/format Content-Type: application/json { "text": "10.1038/nphys1170\nPMID: 34812345\n9780306406157", "style": "vancouver", "locale": "en-US", "output": "text", "footnote": false } ``` Fields: - `text` (string) - one identifier per line, or free text. Mixed types OK. - `style` (string, optional) - citation style ID. Builtins: `vancouver`, `ama`, `apa`, `ieee`, `cse`. Also accepts any CSL style ID. Defaults to `vancouver`. - `locale` (string, optional) - CSL locale, e.g. `en-US`, `en-GB`. - `output` (string, optional) - `"text"` or `"html"`. Defaults to `"text"`. - `footnotes` (boolean, optional) - when `output=html`, render as footnotes. **Response:** ```json { "ok": true, "formatter": "builtin", "styleRequested": "vancouver", "styleUsed": "vancouver", "lang": "en-US", "footnote": false, "outputMode": "text", "orderApplied": "input", "itemsIn": 1, "itemsOut": 1, "items": [ { "id": "doi:10.1038/nphys1170", "type": "journal-article", "title": "Measured measurement", "idx": 0, "sourceIdxs": [0] } ], "html": "Aspelmeyer M. Measured measurement. Nature Phys. 2009;5(1):11-12. doi:10.1038/nphys1170.", "text": "Aspelmeyer M. Measured measurement. Nature Phys. 2009;5(1):11-12. doi:10.1038/nphys1170.", "warnings": [], "meta": { "linesIn": 1, "resolved": 1, "notFound": 0, "errored": 0 } } The formatted citation is the whole-batch `text` (or `html`) string, newline-joined across items. There is no per-item `formatted` field, and unresolved identifiers are counted in `meta` (`notFound` / `errored`) rather than returned as per-item errors. ``` Response headers: `X-Scholar-Cache`, `X-Scholar-Formatter` (builtin|csl), `X-Scholar-Style`, `X-RateLimit-*` **cURL example:** ```bash curl -sS -X POST "https://scholar-sidekick.com/api/format" \ -H "Content-Type: application/json" \ -d '{"text":"10.1038/nphys1170","style":"vancouver","output":"text"}' ``` --- ### POST /api/format/stream Streaming NDJSON variant. Emits one JSON object per line: `start` → `item` (one per identifier) → `done`. ```bash curl -N -sS -X POST "https://scholar-sidekick.com/api/format/stream" \ -H "Content-Type: application/json" \ -d '{"text":"10.1038/nphys1170\nPMID:34812345","style":"apa","output":"html"}' ``` --- ### POST /api/format-items Like `/api/format` but accepts already-resolved CSL JSON items - skips the resolution step. ```json { "items": [ /* CSL-JSON bibliographic items */ ], "style": "apa", "output": "text" } ``` --- ### POST /api/export Exports citations to a bibliography file format. ```http POST /api/export Content-Type: application/json { "text": "10.1038/nphys1170\n9780306406157", "format": "ris", "style": "vancouver" } ``` Fields: - `text` (string) OR `items` (CSL-JSON[]) - input identifiers or pre-resolved items. - `format` (string, required) - export format. - `style` (string, optional) - citation style (used for `txt` format). Supported formats: | format | Description | |---|---| | `ris` | Research Information Systems (EndNote, Zotero, Mendeley) | | `bibtex` | BibTeX (LaTeX, Overleaf, JabRef) | | `csl-json` | Raw CSL-JSON structured metadata | | `endnote-xml` | EndNote XML | | `refworks` | RefWorks tagged format | | `nbib` | MEDLINE/NBIB | | `rdf` | Zotero RDF | | `csv` | Comma-separated values | | `txt` | Formatted plain-text citations | Response — unlike the other endpoints, the body is the export file itself as a plain string, not JSON. `Content-Type` varies by `format`, and `Content-Disposition` names the file: ```http 200 OK Content-Type: application/x-research-info-systems; charset=utf-8 Content-Disposition: attachment; filename="citations.ris"; filename*=UTF-8''citations.ris TY - JOUR AU - Aspelmeyer, Markus TI - Measured measurement JO - Nature Physics PY - 2009 VL - 5 IS - 1 SP - 11 EP - 12 DO - 10.1038/nphys1170 UR - https://doi.org/10.1038/nphys1170 ER - ``` ```bash curl -sS -X POST "https://scholar-sidekick.com/api/export" \ -H "Content-Type: application/json" \ -d '{"text":"10.1038/nphys1170\n9780306406157","format":"ris","style":"vancouver"}' \ -o citations.ris ``` --- ### GET /api/csl/styles Discover available CSL citation styles. Supports search and pagination via query parameters. ### GET /api/health Liveness check. Returns `{ "status": "ok", "time": "" }`. ### Command-line CLI The same REST endpoints are wrapped by the `scholar-sidekick-cli` npm package (command: `scholar`), for terminal and shell-script use. No key required for the free tier. - npm: https://www.npmjs.com/package/scholar-sidekick-cli - GitHub: https://github.com/mlava/scholar-sidekick-cli ```bash npm i -g scholar-sidekick-cli scholar format 10.1038/nphys1170 --style apa scholar export PMID:30049270 --format ris > refs.ris scholar verify --title "Some title" --doi 10.1038/nphys1170 ``` Commands: `format`, `resolve`, `export`, `format-items`, `stream`, `verify`, `retraction`, `oa`, `styles`, `health`. Add `--json` for machine-readable output; `--rapidapi-key` raises rate limits. ### Python client The same REST endpoints are wrapped by the `scholar-sidekick` PyPI package, for scripts, notebooks and Python agents. Sync and async clients. No key required for the free tier. - PyPI: https://pypi.org/project/scholar-sidekick/ - GitHub: https://github.com/mlava/scholar-sidekick-python ```bash pip install scholar-sidekick ``` ```python from scholar_sidekick import ScholarSidekick client = ScholarSidekick() # anonymous; api_key="ssk_..." raises limits client.format(text="10.1038/nphys1170", style="apa").text client.export(text="PMID:30049270", format="ris") client.verify(title="Some title", doi="10.1038/nphys1170").verdict # matched | mismatch | ambiguous | not_found # Audit a bibliography of ANY length: chunks past the per-call cap, paces itself # against the rate limit, and records a failed chunk instead of losing the run. report = client.audit_bibliography(references) report.summary # verdict counts report.needs_review # entries a human should check report.to_dataframe() # requires the [pandas] extra ``` Methods: `format`, `format_items`, `export`, `verify`, `audit`, `audit_bibliography`, `health`. `AsyncScholarSidekick` mirrors them all. Exceptions are selected on the API's stable error `code`, and a `mismatch` verdict is a return value, never an exception. ### Gemini CLI extension / Antigravity plugin The MCP server and CLI are bundled as a [Gemini CLI](https://geminicli.com) extension (also importable as an Antigravity plugin). It exposes the six MCP tools the agent calls autonomously plus `/scholar:*` slash commands. Pure config, no key required. - GitHub: https://github.com/mlava/scholar-sidekick-gemini - Gallery (listed in the official Gemini CLI extension gallery): https://geminicli.com/extensions/?name=mlavascholar-sidekick-gemini - Install: `gemini extensions install https://github.com/mlava/scholar-sidekick-gemini` - Antigravity: `agy plugin import gemini` --- ## 6. MCP Server **URL:** https://scholar-sidekick.com/mcp **Markdown:** https://scholar-sidekick.com/mcp.md **npm package:** scholar-sidekick-mcp Scholar Sidekick is available as a Model Context Protocol (MCP) server. AI assistants such as Claude, Cursor, and other MCP-compatible clients can resolve scholarly identifiers, format citations, and export bibliography files directly within a conversation. ### Available tools **resolveIdentifier** - Resolve DOIs, PMIDs, PMCIDs, ISBNs, arXiv IDs, ISSNs, ADS bibcodes, and WHO IRIS URLs to structured bibliographic metadata (title, authors, journal, year, identifiers). **formatCitation** - Format one or more identifiers into a specific citation style. Supports Vancouver, AMA, APA, IEEE, CSE, and 10,000+ CSL styles. Output as text, HTML, or JSON. **exportCitation** - Export one or more identifiers to bibliography file formats: BibTeX, RIS, CSL JSON, EndNote (XML and Refer), RefWorks, MEDLINE/NBIB, Zotero RDF, CSV, or plain text. All three tools accept multiple identifiers in a single request (separated by newlines). ### Authentication Authenticates via a RapidAPI key. A free tier is available. Get a key: https://rapidapi.com/scholar-sidekick-scholar-sidekick-api/api/scholar-sidekick ### Setup - Claude Desktop Add to `~/Library/Application Support/Claude/claude_desktop_config.json`: ```json { "mcpServers": { "scholar-sidekick": { "command": "npx", "args": ["-y", "scholar-sidekick-mcp@latest"], "env": { "RAPIDAPI_KEY": "your-rapidapi-key" } } } } ``` ### Setup - Claude Code ```bash claude mcp add scholar-sidekick \ -e RAPIDAPI_KEY=your-rapidapi-key \ -- npx -y scholar-sidekick-mcp@latest ``` ### Setup - Cursor / VS Code / Windsurf Add to `.cursor/mcp.json` or `.vscode/mcp.json`: ```json { "mcpServers": { "scholar-sidekick": { "command": "npx", "args": ["-y", "scholar-sidekick-mcp@latest"], "env": { "RAPIDAPI_KEY": "your-rapidapi-key" } } } } ``` ### Environment variables | Variable | Required | Description | |---|---|---| | `RAPIDAPI_KEY` | Yes | Your RapidAPI subscription key | | `RAPIDAPI_HOST` | No | RapidAPI host (default: `scholar-sidekick.p.rapidapi.com`) | | `SCHOLAR_SIDEKICK_TIMEOUT_MS` | No | Request timeout in ms (default: 30000) | ### Example usage - "Format 10.1056/NEJMoa2033700 in Vancouver style" - "Resolve PMID:30049270 and export as BibTeX" - "Format these three identifiers as AMA and save as a RIS file: 10.1056/NEJMoa2033700, PMID:30049270, ISBN:9780192854087" ### MCP registries - GitHub: https://github.com/mlava/scholar-sidekick-mcp - MCP Registry: https://registry.modelcontextprotocol.io/v0.1/servers?search=scholar-sidekick - mcpservers.org: https://mcpservers.org/servers/mlava/scholar-sidekick-mcp - mcp.so: https://mcp.so/server/scholar-sidekick-mcp/mlava - PulseMCP: https://www.pulsemcp.com/servers/mlava-scholar-sidekick-mcp --- ## 7. Browser Extension **URL:** https://scholar-sidekick.com/extension Scholar Sidekick is available as a free browser extension for Chrome, Firefox, and Edge. Users right-click any selected text containing a scholarly identifier (DOI, PMID, PMCID, ISBN, arXiv ID, ADS bibcode, or scholarly URL) on any web page and choose "Cite with Scholar Sidekick" to get a formatted citation in a small popup, ready to copy. ### How it works 1. Select text on any web page that contains a scholarly identifier. 2. Right-click and choose "Cite with Scholar Sidekick" from the context menu. 3. A small popup opens with the selection auto-formatted as a citation in the chosen style. 4. Click Copy. Paste into manuscript, essay, or reference list. ### Identifier and style support The extension is a thin client over the public `/api/format` and `/api/csl/styles` endpoints. Output formatting is identical between extension and website. - Identifiers: DOI, PubMed ID (PMID), PMC ID (PMCID), ISBN-10/13, arXiv ID (modern and legacy), NASA ADS bibcode, scholarly URLs. - Quick-pick citation styles: Vancouver, APA, AMA, IEEE, CSE. - Searchable combobox over 10,000+ CSL styles (Nature, Cell, Lancet, Chicago, Harvard, journal-specific styles). - Last-used style remembered locally for next time. ### Privacy The extension contains no content scripts. It does not read page contents, browsing history, or anything else from the pages the user visits. It only ever sees text the user explicitly selects and submits via the right-click menu. Selected text is sent to scholar-sidekick.com to produce the citation, then discarded. No analytics, no advertising trackers, no user accounts. Permissions used: - `contextMenus` - registers the right-click menu item. - `storage` - remembers the user's last-used style locally (chrome.storage.local). - `host_permissions: https://scholar-sidekick.com/*` - calls the citation API. No other hosts. No ``. ### Cross-browser A single TypeScript source tree is bundled (esbuild, IIFE) for three targets: Chrome Web Store, Firefox Add-ons (AMO), Edge Add-ons. Manifest V3. ### Deep-link to the website The popup includes an "Open in Scholar Sidekick →" link that carries the user's selection and chosen style across to the full editor at scholar-sidekick.com via URL parameters (`?text=&style=`) - no copy/paste needed. Useful when the user needs the full editor: multiple references, footnote mode, or batch export to BibTeX, RIS, EndNote XML, CSV, or Markdown. --- ## 8. Explainer **URL:** https://scholar-sidekick.com/explainer **Markdown:** https://scholar-sidekick.com/explainer.md Scholar Sidekick is a lightweight citation-export tool for one-off academic and clinical needs. It is designed to complement existing reference managers, not replace them. ### What Scholar Sidekick is Scholar Sidekick helps users quickly generate correct, predictable citation outputs from common scholarly identifiers such as DOIs, PMIDs, ISBNs, and URLs. It is intentionally lightweight and web-based, usable without an account for one-off tasks, focused on deterministic citation output, and suitable for short, self-contained tasks. The emphasis is on clarity, correctness, and minimal overhead. ### What Scholar Sidekick is not Scholar Sidekick is deliberately not a full reference manager. It does not aim to manage long-term citation libraries, store or organise collections of references, replace tools such as Zotero, EndNote, or Mendeley, or support collaborative library management. For long manuscripts, theses, or ongoing research projects, a dedicated reference manager remains the appropriate tool. ### When Scholar Sidekick is useful Scholar Sidekick is well suited to preparing talks or lectures, creating conference posters or abstracts, drafting grant applications or committee documents, teaching materials or course handouts, journal clubs or guideline summaries, and any task requiring a small number of citations quickly and correctly. These are time-constrained, one-off workflows where setting up or maintaining a citation library is unnecessary overhead. ### Why it exists We repeatedly saw people struggle with needing a handful of references quickly, inconsistent citation output across tools, the friction of creating or maintaining a library for short tasks, and unclear or unpredictable CSL behaviour. Scholar Sidekick exists to address that narrow gap - and nothing more. ### Design principles The tool is built around a small set of constraints: deterministic output (the same input produces the same result), minimal state (no required accounts, no long-term storage by default), standards-aware (careful handling of citation styles and formats), and transparency (predictable behaviour, no hidden automation). ### Safety, privacy, and trust No account is required for the core, one-off usage of the tool. Citation inputs are processed on demand and not stored after the request completes. Only minimal operational logs are retained. There is no advertising, tracking, or profiling. ### When you should not use Scholar Sidekick Scholar Sidekick is probably not the right tool if you are writing a thesis or long manuscript, you need ongoing citation library management, you collaborate on shared reference databases, or you require advanced annotation or note-taking features. In those cases, a full reference manager will serve you better. --- ## 9. Engineering Principles **URL:** https://scholar-sidekick.com/engineering-principles Scholar Sidekick is built as deterministic citation infrastructure. These principles guide development and deployment. ### Determinism First Identical inputs produce identical outputs. CSL styles and locales are pinned to specific versions to prevent silent behavioral drift. ### Contract Stability Public API behavior does not change without explicit versioning. Headers, error semantics, and export structures are treated as contract guarantees. ### Thin Adapters Marketplace integrations and MCP servers wrap the canonical HTTP API. No formatting or resolution logic is duplicated outside the core service. ### Spec Fidelity Export formats conform to their published specifications. Outputs are validated through semantic tests rather than brittle snapshots. ### Observable Infrastructure Request identifiers, rate-limit headers, and health endpoints are consistently exposed to support operational transparency. ### Minimal Data Retention Requests are processed on demand. Raw citation inputs are not retained as application data after processing. ### Versioned, Logged Changes The normalisation/formatter/resolver chain is tagged with `x-scholar-transform-version` and the verifier pipeline with `x-scholar-verify-version`. Every bump is recorded in the changelog at https://scholar-sidekick.com/changelog (markdown: https://scholar-sidekick.com/changelog.md), each entry tagged output-affecting, verdict-affecting, breaking, or non-breaking, so integrators can detect drift and re-baseline pinned output. The current `transform_version` is mirrored in https://scholar-sidekick.com/.well-known/sources.json. Service availability — rolling uptime and incident history for the public API — is published at https://status.scholar-sidekick.com (own-API status only; upstream metadata-source health is a separate informational section), with the same URL mirrored in sources.json as `status_url`. --- ## 10. Accessibility **URL:** https://scholar-sidekick.com/accessibility Scholar Sidekick aims to be usable by as many people as possible across both account-free and optional account-based features, including users with disabilities. Accessibility is treated as an ongoing responsibility rather than a one-time checklist. ### Our approach We aim to design and maintain Scholar Sidekick in line with widely accepted accessibility best practices, including the principles of the Web Content Accessibility Guidelines (WCAG). In practice, we focus on clear, readable text and predictable layouts, keyboard-accessible interactions, sensible use of semantic HTML, and avoiding unnecessary animations or visual distractions. ### Testing and review We use a combination of automated checks and manual review, including automated accessibility testing tools, browser-based audits during development, and manual testing of key user flows using keyboard navigation and screen readers. Accessibility testing is performed regularly, particularly when core functionality changes. ### Known limitations Because Scholar Sidekick is a small, evolving service, there may be areas where accessibility can be improved. Examples include third-party content or embedded resources outside our direct control, and edge cases involving unusual assistive technology combinations. We treat identified issues as bugs and aim to address them when they are discovered. ### Feedback and support If you encounter any accessibility barriers while using Scholar Sidekick, we want to hear about them. Please contact us with a description of the issue, the page or feature involved, and the assistive technology or browser you are using (if relevant). Email: accessibility@scholar-sidekick.com. We take accessibility feedback seriously and will do our best to respond promptly. ### Ongoing improvement Accessibility work is iterative. As the service evolves, we aim to continue improving accessibility alongside new features and fixes. --- ## 11. Citation integrity in the age of AI {#citation-integrity} **URL:** https://scholar-sidekick.com/citation-integrity **Markdown:** https://scholar-sidekick.com/citation-integrity.md Long-form explainer covering the dominant citation-fabrication pattern documented by Topaz et al. (Lancet 2026, doi:10.1016/S0140-6736(26)00603-3, open access) and how Scholar Sidekick's verifier surface catches it. **Headline finding.** 1 in 277 biomedical papers in early 2026 contains at least one fabricated reference - a more than 12× increase over 2023. Topaz et al. audited 2.5 million PubMed Central articles with a pipeline called CITADEL. The trajectory of the increase strongly implicates the proliferation of large language models in scientific writing. **Why simple DOI checks miss it.** The dominant pattern is *real DOI + invented title*. The identifier resolves; the paper at that identifier is real; but the title in the citation does not correspond to the resolved paper. Clicking the DOI to confirm it resolves is exactly the check the pattern is designed to bypass. The fix is mechanical: compare cited metadata against resolved metadata at the identifier. **Three illustrative cases.** The explainer publishes Topaz et al.'s Supplementary Appendix 2 cases verbatim: - Example A: Split-identifier confusion. Real PMID and real DOI in the same journal, but they resolve to *different real papers*, and the cited title exists in neither. - Example B: Consistent identifiers (PMID and DOI agree), but the resolved paper is unrelated (C. elegans habitats vs. claimed DMM/PTX mouse model protocol). - Example C: Consistent identifiers resolve to an editorial on "ChatGPT in Research"; cited title fabricates a plausible neuroscience study on microglial CB2 receptors and fibromyalgia. **Scholar Sidekick verifier vs CITADEL.** Complementary, not competitive. CITADEL is offline, post-publication, PMC-XML-only, DOI + PMID coverage. Scholar Sidekick is online, on-demand, with 8 identifier types (DOI, PMID, PMCID, ISBN, arXiv, ISSN, ADS bibcode, WHO IRIS URL) - extending the same cross-reference methodology into books, ML/physics preprints, astrophysics, and institutional grey literature. **Latest blind holdout (n = 1,395) - the headline measurement.** The primary evidence is a blind holdout of 1,395 freshly-drawn citations (1,185 correctly-cited + 210 fabricated/wrong) across all eight identifier types, ~4x the earlier 350-entry holdout. Drawn 2026-06-05 from a recorded seed after the code was frozen, constructed title-independently, human spot-checked (105/105 sampled), sealed, and measured exactly once. A machine check confirms zero overlap (0 of 855 prior entries) with any set the verifier was previously tuned or measured against. The set was also re-measured a second time (99.9% verdict stability, zero real changes - deterministic) and re-scored with the opt-in LLM screen. Run against production: - Recall: on the dominant fabrication patterns (real-DOI+fabricated-title, wrong-author, wrong-DOI, PMID/DOI-split, fully-invented), 150/150 = 100% (Wilson 95% CI lower bound ~97.6%), each subtype 30/30. - False-accusation rate (clean arm, n = 1,175): high-confidence false-accusations 9 = 0.8% (Wilson 95% CI 0.4-1.4%); of those, confident title mismatches were only 2 = 0.17%. Including the low-confidence bucket, 2.7%. The opt-in LLM screen cuts the any-flag rate to 0.94% (rescued 22 low-confidence clean cases) with ZERO cost to genuine-fabrication recall. Calibration ECE 0.026 (high-confidence verdicts 97% correct). - The two confident false-accusations, in full: neither is a title-logic error - one is author-form handling (a DataCite literal author "de Azcarraga, Jose A." vs the cited "Azcarraga", title matched exactly), one is an Open Library record mis-titling a study guide as its parent textbook (a registry data-quality artifact). Both kept in the count; sealed numbers are not adjusted. - MEASURED BLIND SPOT (near-miss semantic flips): a real title with one load-bearing word flipped to the opposite meaning ("children"->"adults", "increases"->"decreases") was caught only 4/30 - the other 26 evade as confident matches, because a one-word change barely moves a character-level similarity. Distinct from the AI-fabrication pattern (caught 100%) and closer to a subtle citation error; the LLM screen does not address it (these never enter its low-confidence gate). Planned fix: a targeted antonym/negation detector. Reported, not omitted. - The loop, disclosed and continued: a first blind run measured 5.3% (95% CI 3.2-8.7%) and surfaced a dataset-construction bug plus two verifier gaps (initials-first author names, a missing "Collaborators" group marker), all fixed (changelog 2026-05-26); a fresh 350-entry holdout then measured 1.8% (95% CI 0.8-4.0%); then three further normalization known-hards were fixed (Greek-letter, numeric-HTML-entity, Latin-extended title handling, changelog 2026-06-05) and the holdout was enlarged ~4x and re-drawn fresh - the n=1,395 run above, whose larger sample brought the high-confidence false-accusation upper bound under 3% and surfaced the near-miss blind spot. All runs published with full receipts below. **Measured numbers (v1 fixture, n = 20).** Hand-curated 20-entry validation set with three categories sourced from Topaz et al.'s appendix verbatim and the rest from independent registry lookups via Crossref / PubMed / arXiv. All figures are recomputed from the published receipts (downloadable JSON below); each receipt's per-entry `results` array carries the verdict, confidence, and resolution source for every case, so these numbers can be recomputed from the JSON alone - no access to our code required. Confidence intervals are Wilson 95%, wide on purpose because the fixture is small and hand-verified. - Verdict conformance: all 20 entries returned their expected verdict in both modes (the receipts' `metrics` block records this as precision = recall = F1 = 1.000 on the harness's expected-verdict basis). - Fabrication recall: 11 of 11 flagged - 100%, 95% CI 74-100%. - False-accusation rate (clean citations wrongly flagged, the number that matters most for a verifier): 0 of 9 high-confidence false flags in both modes (95% CI 0-30%); including low-confidence flags, 4 of 9 pre-LLM (paraphrase cases routed to the LLM screen) falling to 0 of 9 with the screen enabled. - Differentiator (real DOI + wrong title, the dominant Topaz pattern): the verifier catches 7 of 7 (95% CI 65-100%); a plain "does the identifier resolve?" check catches 0 of 7, because the identifiers do resolve - to the wrong paper. - LLM cost: ~0.001 USD per applied screen. Latency p50 ~ 2 s, p95 ~ 10 s (pre-LLM, point-in-time). These v1 numbers are a reproducible methodology check on 20 hand-picked adversarial cases, not a population-scale accuracy claim - the intervals are wide because n = 20. The 1,395-entry blind holdout above is the larger clean arm that tightens the false-accusation-rate bound. The fixtures are marked immutable; each new measurement gets its own versioned, immutable fixture (the blind holdouts are `validation-set-v4-blind.json`, `validation-set-v3-blind.json`, and `validation-set-v2-blind.json`), and old numbers always cite the specific fixture version. **Receipts (downloadable JSON):** - https://scholar-sidekick.com/citation-integrity/validation-set-v4-blind.json (the sealed 1,395-entry blind holdout - seed, partitions, per-subtype attack types, disjointness check, spot-check record) - https://scholar-sidekick.com/citation-integrity/validation-results-v4-blind-pre-llm.json (the headline single measure-once receipt) - https://scholar-sidekick.com/citation-integrity/validation-results-v4-blind-with-llm.json (the same sealed set re-scored with the opt-in LLM screen on) - https://scholar-sidekick.com/citation-integrity/validation-results-v4-blind-pre-llm-run2.json (the repeatability re-run, 99.9% stable) - https://scholar-sidekick.com/citation-integrity/validation-set-v3-blind.json (the sealed 350-entry blind holdout - seed, partitions, disjointness check, spot-check record) - https://scholar-sidekick.com/citation-integrity/validation-results-v3-blind-pre-llm.json (the 350-entry holdout's single measure-once receipt) - https://scholar-sidekick.com/citation-integrity/validation-set-v2-blind.json (the first/discovery holdout, built with the dataset-construction bug since fixed) - https://scholar-sidekick.com/citation-integrity/validation-results-v2-blind-pre-llm.json (the discovery run's receipt - the 5.3% rate that surfaced the bugs) - https://scholar-sidekick.com/citation-integrity/validation-set-v1.json - https://scholar-sidekick.com/citation-integrity/validation-results-pre-llm.json - https://scholar-sidekick.com/citation-integrity/validation-results-with-llm.json - https://scholar-sidekick.com/citation-integrity/known-failures.md (the verifier's known weak cases and current limitations) **Primary reference.** Topaz M, Roguin N, Gupta P, Zhang Z, Peltonen L-M. *Fabricated citations: an audit across 2·5 million biomedical papers.* The Lancet. 2026;407(10541):1779-1781. doi:10.1016/S0140-6736(26)00603-3. --- ## 12. Comparisons: Best AI Citation Verifier in 2026 {#compare-best-ai-citation-verifier} **URL:** https://scholar-sidekick.com/compare/best-ai-citation-verifier **Markdown:** https://scholar-sidekick.com/compare/best-ai-citation-verifier.md > From a clinical researcher who reads citations weekly. I built one of the ten tools on this page (Scholar Sidekick). I tried to write the comparison the way I would want to read it. > Last updated: 2026-05-14 > HTML version: https://scholar-sidekick.com/compare/best-ai-citation-verifier In early 2026, Topaz et al. audited 2.5 million biomedical papers and found that roughly 1 in 277 contains at least one fabricated reference (Lancet 2026;407(10541):1779-1781). The dominant fabrication pattern is not what people expect: it is not the obviously fake DOI or the made-up journal name. It is a *real, resolvable DOI* paired with an *invented title and abstract*. The identifier checks out. The metadata does not match. A naive DOI-resolver-only check passes. The verifier category exists because that pattern is hard. There are now at least ten dedicated tools that try to detect it, mostly launched in the past 18 months in response to ChatGPT/Claude/Gemini-generated reference lists slipping past peer review. This page is an honest roundup of those ten: what each is for, what it costs, what databases it cross-references, and which one I would reach for in each situation. The methodology is simple - I visited each tool's product page on [2026-05-14](https://scholar-sidekick.com/citation-integrity) and recorded what they say they do. One framing note up front. I built one of the ten tools on this page ([Scholar Sidekick](https://scholar-sidekick.com/tools/citation-verifier)). The page is not a sales pitch - several of the other nine win cleanly on specific axes (PDF upload, manuscript-wide passes, education-focused integrations, generous free tiers). What Scholar Sidekick is built for is *source-of-truth metadata across the broadest identifier surface I could assemble*: DOI, PMID, PMCID, ISBN, ISSN, arXiv, ADS bibcode, WHO IRIS URL. Plus retraction-awareness via Retraction Watch and open-access classification via Unpaywall, plus a free public MCP server for AI agents. If those things matter to your workflow, the case for Scholar Sidekick gets stronger. If they do not, one of the others is probably the right answer. ### Pick a verifier in 30 seconds Each tool is built for a specific workflow. If you recognise yours below, that is probably the right tool for you - the rest of the page is the longer version of the same answer. - **Verifying biomedical, clinical, or systematic-review references with retraction-awareness?** → [Scholar Sidekick](https://scholar-sidekick.com/tools/citation-verifier) (free, no signup; broader identifier surface; live Retraction Watch + Unpaywall; public MCP server). - **Screening student essays for hallucinated citations in an educational setting?** → [GPTZero Source Finder](https://gptzero.me/sources) (education-focused, Canvas / Google Classroom integration, 1M+ educators). - **Need an AI assistant that suggests *replacement* citations when it flags a fake?** → [Sourcely](https://www.sourcely.net/citation-verification) (returns ready-to-use replacements; broad database coverage). - **Want to call a verifier from your own agent or pipeline via MCP?** → [Scholar Sidekick MCP](https://scholar-sidekick.com/mcp) (only verifier on this page with a public MCP server). - **Paying user who wants a polished UI with team libraries and a chat assistant?** → [Citely](https://citely.ai) ($14-19/month; 95% accuracy claim; team workspaces; chat guidance). - **Free tier only, occasional use, generic AI-fabricated reference?** → [CiteTrue](https://citetrue.com) (positions as the free option) or [AiCitationChecker](https://aicitationchecker.org) (50 free credits/day, no signup). Scholar Sidekick is not the right choice if you need PDF upload, manuscript-wide structural checks, plagiarism detection, Word-document export of corrected references, or replacement-citation suggestions - other tools on this page win on each of those axes. ### When to use which verifier | If you need... | Reach for | Why | | --- | --- | --- | | Source-of-truth metadata across the broadest identifier surface (DOI, PMID, PMCID, ISBN, ISSN, arXiv, ADS, WHO IRIS) | Scholar Sidekick | Only verifier on this page that resolves PMCID, ADS bibcode, ISSN, and WHO IRIS URL alongside the common DOI/PMID/arXiv set. | | Retraction-awareness as part of citation verification | Scholar Sidekick | Only verifier on this page with live Retraction Watch integration (separate /tools/retraction-checker, plus enrichment on the main verifier). | | Open-access status with a free legal PDF link | Scholar Sidekick | Live Unpaywall integration with Gold/Green/Hybrid/Bronze classification via /tools/open-access-checker. | | MCP server so an AI agent can verify citations on demand | Scholar Sidekick MCP | Only verifier on this page with a first-party MCP server. `verifyCitation` is one of six tools. | | Education / classroom setting (essays, plagiarism context, Canvas / Google Classroom integration) | GPTZero Source Finder | Built for educators screening student work; integrates with the LMS stack that schools already use. | | Replacement citations when a fake is flagged | Sourcely | Returns formatted ready-to-use real citations, not just a flag. Closest to the 'find me a real source for this claim' workflow. | | Polished paid UI with chat assistant and team libraries | Citely | $14-19/month, claims 95% accuracy, has a research-assistant chat and team workspaces. The most consumer-friendly verifier of the ten. | | Generous free tier for occasional use, no signup | AiCitationChecker or CiteTrue | AiCitationChecker gives 50 free credits/day with no signup; CiteTrue positions itself as the free option. | | Catching the dominant 'real DOI + invented title' fabrication pattern documented by Topaz et al. (Lancet 2026) | Scholar Sidekick | Only verifier on this page that names the Topaz pattern explicitly and is designed around it. | | Deterministic, version-pinned verifier output for an audit or publication | Scholar Sidekick | x-scholar-transform-version header pins the resolver chain, normalisation, comparator, and CSL engine to a specific snapshot. No other verifier on this page publishes a deterministic-output contract. | | Verifying a whole manuscript file (.docx, .tex, .md) end-to-end | Scribbr / Paperpal / Recite | These are structural manuscript tools - in-text-to-bibliography matching, formatting consistency, manuscript-wide passes. Different category from fabrication detection; pair with one of the verifiers above. | ### At a glance | Tool | Free tier | Paid | Databases | Identifier surface | Retraction / OA | API / MCP | Source claim | | --- | --- | --- | --- | --- | --- | --- | --- | | Scholar Sidekick | Free anonymous tier with rate limit; no signup | Paid tiers via RapidAPI ($0-$249/mo) | Crossref, PubMed, DataCite, arXiv, ADS, OpenLibrary, WHO IRIS, Unpaywall, Retraction Watch | DOI, PMID, PMCID, ISBN, ISSN, arXiv, ADS bibcode, WHO IRIS URL | Both (Retraction Watch via /tools/retraction-checker; Unpaywall via /tools/open-access-checker) | Public REST API + first-party MCP server with `verifyCitation` tool | Topaz et al. (Lancet 2026) fabrication-pattern detection; deterministic transform_version header | | Citely | $9 one-time trial (15 credits, ~8-15 refs) | $14-19/mo or $347 lifetime | Crossref, PubMed, arXiv, Google Scholar, OpenAlex, Semantic Scholar | Not stated | Not mentioned | Not mentioned | 95% accuracy claim | | CiteTrue | Free tier (positioned as the free option) | Not stated on landing page | Multiple academic databases (not enumerated) | Not stated | Not mentioned | Not mentioned | '#1 free AI-powered citation verification tool' | | GPTZero Source Finder | Free up to 10,000 characters | Paid tiers (educator-focused) | 220M scholarly articles, preprints, real-time news | Not identifier-first; works on pasted text | Not mentioned | Public API + Chrome extension + Canvas + Google Classroom + Zapier | 99% accuracy on latest AI-detection benchmark | | Sourcely | Free tier with limits | $19-39/mo (annual) | Google Scholar, Semantic Scholar, Crossref, PubMed, arXiv, Scopus, Web of Science, JSTOR, CORE | Not identifier-first; APA/MLA/Chicago/Harvard citation strings | Not mentioned | Not mentioned | 200M peer-reviewed papers; detects ChatGPT/Claude/Gemini/Perplexity hallucinations | | TrueCitation | Free (positioned as 'free source reliability checker') | Not stated on landing page | 17+ academic databases (not enumerated) | Citation strings, journals, URLs | Predatory-publisher detection (different signal) | Not mentioned | Detects AI-fabricated references and predatory publishers | | AiCitationChecker | 50 credits/day, no signup | $9.99-$99.99 packs (90-180 days) | Crossref, OpenAlex, Semantic Scholar | Citation strings in any format | Not mentioned | Mentioned in footer ('For AI Agents'); not detailed | 95% match rate for DOI references; in-memory only (no data retention) | | CiteMe AI Reference Verifier | Not stated on landing page | Not stated | 250M+ academic sources | AI-generated references from ChatGPT, Gemini, Claude | Not mentioned | Not mentioned | Catch hallucinated citations before submitting | | SwanRef | Not stated | Not stated | 150M papers via Crossref + Google Scholar | Not stated | Not mentioned | Not mentioned | AI hallucination detector for academic citations | | CiteSure | Not stated | Not stated | Not enumerated | Citation strings | Not mentioned | Not mentioned | AI-powered citation verification | ### The ten verifiers *Each capsule below reflects what I found on the tool's product page on 2026-05-14, plus what the AI engines (ChatGPT, Perplexity, Google AI Overviews) report when asked about each tool. Pricing, free-tier limits, database lists, and accuracy claims change frequently - verify the linked product page before subscribing.* #### Scholar Sidekick - source-of-truth metadata with retraction-awareness *Free citation verifier with the broadest identifier surface on this page, live retraction and open-access status, and a public MCP server. The project I built.* [Scholar Sidekick's citation verifier](https://scholar-sidekick.com/tools/citation-verifier) resolves any of eight identifier types - DOI, PMID, PMCID, ISBN, ISSN, arXiv, ADS bibcode, WHO IRIS URL - against the live upstream registries (Crossref, PubMed, DataCite, arXiv, ADS, OpenLibrary, WHO IRIS) and compares the resolved title to the claimed title. When the identifier resolves but the titles disagree, it flags the dominant fabrication pattern documented by [Topaz et al. (Lancet 2026)](https://doi.org/10.1016/S0140-6736(26)00603-3): a real, resolvable DOI paired with an invented title. That pattern is the one a naive DOI-resolver-only check passes. Verification is shipped three ways: a free web tool at [/tools/citation-verifier](https://scholar-sidekick.com/tools/citation-verifier) (no signup, rate-limited), a public REST endpoint at /api/verify, and a first-party MCP server (`scholar-sidekick-mcp` on npm) that exposes `verifyCitation` alongside `resolveIdentifier`, `formatCitation`, `exportCitation`, `checkRetraction`, and `checkOpenAccess`. The MCP server is the only one on this page; if you are building an AI-agent pipeline that needs to verify a citation as part of a longer workflow, that matters. What is distinctive: retraction-awareness via [Retraction Watch](https://scholar-sidekick.com/tools/retraction-checker) is built in, open-access status via [Unpaywall](https://scholar-sidekick.com/tools/open-access-checker) is built in, the identifier surface covers astrophysics (ADS), global health (WHO IRIS), and biomedical edge cases (PMCID), and every response carries an `x-scholar-transform-version` header that pins the resolver chain, normalisation, comparator, and CSL engine to a specific snapshot. None of the other nine tools publish a versioned-output contract; if your verifier runs against the same DOI six months from now, you cannot tell from any of them whether a change in output is a real change in upstream metadata or a silent change in their processing chain. - **Free tier.** Anonymous web access with a published rate limit; no signup, no account, no PDF upload. Paid tiers via [RapidAPI](https://rapidapi.com/scholar-sidekick-scholar-sidekick-default/api/scholar-sidekick) for higher request limits ($0-$249/month). - **Identifier surface.** DOI, PMID, PMCID, ISBN, ISSN, arXiv, ADS bibcode, WHO IRIS URL. PMCID and ADS bibcode coverage matter for biomedical preprints and astrophysics; WHO IRIS for global health policy documents. - **Retraction-awareness.** Live Retraction Watch via Crossref integration. Available as a dedicated [/tools/retraction-checker](https://scholar-sidekick.com/tools/retraction-checker), as a public API endpoint, as per-item enrichment on /api/format via `?checks=retraction`, and as the `checkRetraction` MCP tool. - **Open-access status.** Live Unpaywall integration with Gold / Green / Hybrid / Bronze classification. Available as a dedicated [/tools/open-access-checker](https://scholar-sidekick.com/tools/open-access-checker), as a public API endpoint, as per-item enrichment via `?checks=oa`, and as the `checkOpenAccess` MCP tool. - **Deterministic output.** `x-scholar-transform-version` header pins the resolver chain, normalisation, formatter, comparator, and CSL engine to a specific snapshot. Identical inputs at a fixed transform version produce byte-identical output for a cache hit. Cache hits are exposed via `x-scholar-cache` so changes are explainable. - **Where it does not win.** No PDF upload (paste-only), no Word-document export of corrected references, no plagiarism detection, no replacement-citation suggestions, no team libraries, no chat assistant. If your workflow needs any of those, one of the other tools on this page is the better choice. #### Citely - paid consumer-friendly verifier with chat assistant *AI-powered citation checker with a polished paid UI, chat assistant, and team workspaces. The most consumer-facing verifier on this page.* [Citely](https://citely.ai) (citely.ai) is the most actively-marketed verifier in the category. It cross-references citations against Crossref, PubMed, arXiv, Google Scholar, OpenAlex, and Semantic Scholar, and claims a 95% accuracy rate on detecting fabricated vs authentic citations. Pricing starts at a $9 one-time trial (15 credits, 2,000 characters - about 8 to 15 references), then $19/month or $14/month billed annually, with a $347 lifetime ('Believer') tier. The product page emphasises an AI research-assistant chat, team workspaces with shared libraries, and integrations with Zotero, Mendeley, and EndNote. Citely is the verifier I most expect a paying student or researcher to land on through advertising or AI-engine recommendations - it is the most-cited tool on Perplexity and Google AI Overviews for 'fake citation detector' queries in our 2026-05-14 baseline, including a 'Best AI Citation Checker in 2026' blog post that Google AI Overviews cites verbatim. The product is polished and the audience-fit for a paying user is real. Where Citely does not differentiate from the rest of this list: identifier coverage (DOI/PMID/arXiv only as far as the landing page describes), retraction-awareness (not mentioned), open-access status (not mentioned), public API (not mentioned), MCP server (none), or a published deterministic-output contract. - **Pricing.** $9 trial / $14-19/month / $347 lifetime. Credit-based (character-counted). - **Databases.** Crossref, PubMed, arXiv, Google Scholar, OpenAlex, Semantic Scholar. - **Strengths.** Polished UI, chat assistant, team workspaces, integrations with Zotero / Mendeley / EndNote, the strongest marketing presence in the category. - **Gaps for biomedical or systematic-review workflows.** No PMCID, ADS, or ISSN support per the landing page; no retraction or open-access surface; no MCP; no versioned-output contract. #### CiteTrue - positions as the free citation checker *Free AI-powered citation verifier; the consistent 'free option' brand in AI-engine recommendations for this category.* [CiteTrue](https://citetrue.com) (citetrue.com) is the free counterpart to Citely in AI-engine recommendation lists for the fake-citation-detector category. The site styles itself as the '#1 free AI-powered citation verification tool' and is cited consistently across ChatGPT, Perplexity, and Google AI Overviews on the verifier queries we tracked. It searches 'vast authoritative academic databases' (not enumerated on the landing page) to verify citations and flag fabricated or AI-generated references. What is hard to assess: the landing page does not enumerate which databases are queried, does not state identifier coverage, and does not describe the verification algorithm. It is free, which is real - most other tools in this list charge once you pass a small free quota - but the lack of detail makes it hard to evaluate against a specific workflow. If you need a free first-pass triage tool and do not require retraction status, identifier-surface guarantees, or replacement-citation suggestions, CiteTrue is a reasonable choice. - **Pricing.** Free (no paid tier described on the landing page). - **Strengths.** No-cost first-pass triage; strong AI-engine recommendation presence; positions as the free option in the category. - **Gaps.** Databases not enumerated; identifier surface not specified; no API; no MCP; no retraction or open-access status. #### GPTZero Source Finder - education-focused hallucination detector *Education-first hallucinated-citation detector integrated with Canvas, Google Classroom, and Zapier. Different primary audience from the others.* [GPTZero Source Finder](https://gptzero.me/sources) is GPTZero's citation-verification surface, built on the same brand and infrastructure as their AI-text detector. It scans pasted essays for hallucinated citations and unsupported claims, cross-references against 220 million scholarly articles plus preprints and real-time news, and provides line-specific analysis with source recommendations for unsupported claims. Free tier allows up to 10,000 characters; paid tiers and a public API are available. GPTZero's primary audience is *educators screening student work*, not researchers verifying their own bibliographies. The product reflects that: there are 1 million educators on the platform, Canvas and Google Classroom integrations, multilingual support (EN/ES/FR/DE and others), and a Chrome extension. If you are a teacher screening essays for AI-generated content (including hallucinated citations), GPTZero is built for you. If you are a researcher verifying a clinical reference list, the workflow fit is weaker - it is essay-shaped, not bibliography-shaped. - **Pricing.** Free up to 10,000 characters; paid educator tiers above (specific pricing not on the landing page). - **Databases.** 220M scholarly articles, preprints, real-time news. - **Strengths.** Education-focused workflow, LMS integrations (Canvas, Google Classroom, Zapier), public API, Chrome extension, multilingual. - **Different category.** Built for screening student essays, not for verifying a researcher's own bibliography. Closer to GPTZero's AI-detection product than to the source-of-truth verifiers on this page. #### Sourcely - verification plus replacement-citation suggestions *Verifier that also returns ready-to-use real citations when it flags a fake. The closest fit for the 'find me a real source for this claim' workflow.* [Sourcely](https://www.sourcely.net/citation-verification) (sourcely.net) is the verifier most clearly oriented around the 'replace my fake citation with a real one' workflow. It cross-references against an unusually broad database list - Google Scholar, Semantic Scholar, Crossref, PubMed, arXiv, Scopus, Web of Science, JSTOR, and CORE - and explicitly handles AI hallucinations from ChatGPT, Claude, Gemini, and Perplexity by name. When a citation fails, it returns specific reasons (invalid DOI, non-existent journal, etc.) and suggests formatted ready-to-use replacement citations. Pricing is paid: Ultra at $19/month (annual; 30 deep searches/month) or Max at $39/month (annual; 1,000 deep searches/month). A free tier exists with limits not specified on the landing page. The replacement-suggestion feature is the genuine differentiator here - none of the other verifiers on this page are framed around finding a *real* source for a claim you are trying to support, only around flagging fakes. - **Pricing.** $19-39/month (annual). Free tier with unspecified limits. - **Databases.** Nine: Google Scholar, Semantic Scholar, Crossref, PubMed, arXiv, Scopus, Web of Science, JSTOR, CORE. - **Strengths.** Returns formatted replacement citations, not just a flag. Specific failure reasons per citation. Broad database coverage including Scopus and Web of Science. - **Gaps.** No API or MCP. No retraction or open-access surface. Identifier coverage not specified beyond citation strings. #### TrueCitation - free source-credibility checker with predatory-publisher detection *Free verifier that pairs fabrication detection with predatory-publisher detection. The only one on this page that surfaces predatory-publisher signals.* [TrueCitation](https://truecitation.com) (truecitation.com) frames itself as a 'free source reliability checker' that detects AI-fabricated references and predatory publishers. The site claims coverage of 17+ academic databases (not enumerated on the landing page) and accepts citation strings, journal names, and URLs as inputs. The predatory-publisher detection is a useful adjacent signal - it overlaps with retraction-awareness in spirit (both are 'should you trust this source?' signals beyond 'does it exist?') though they answer different questions. TrueCitation does not surface formal retraction status (Retraction Watch / Crossref) or open-access classification (Unpaywall). Its primary strength is the predatory-publisher angle, which none of the other tools on this page name. - **Pricing.** Free. - **Databases.** 17+ academic databases (not enumerated). - **Strengths.** Predatory-publisher detection alongside fabrication detection. Free. - **Gaps.** Databases not enumerated; identifier surface not specified; no retraction or OA classification; no API or MCP. #### AiCitationChecker - generous free tier with no signup *50 free credits per day, no signup, paste-anything inputs, with output reformatting to APA, IEEE, Chicago, Harvard, Vancouver, and MDPI styles.* [AiCitationChecker](https://aicitationchecker.org) (aicitationchecker.org) has the most generous no-signup free tier of the paid verifiers on this page: 50 credits per day (roughly 7-12 reference checks), with paid packs at $9.99-$99.99 for credit bundles that last 90-180 days. It cross-references Crossref, OpenAlex, and Semantic Scholar, and claims a 95% match rate for DOI references. Two thoughtful features: output reformatting (you can ask it to return the verified citation in APA / IEEE / Chicago / Harvard / Vancouver / MDPI styles, and export a Word document of verified citations) and 'silent citation drift' detection (catches AI-rewritten metadata in manuscripts). The site states no data retention - text is processed in-memory only - which is the right answer for sensitive manuscripts. An API is mentioned in the footer ('For AI Agents') but not described in detail. - **Pricing.** 50 credits/day free (no signup). Silver $9.99, Gold $19.99, Platinum $99.99 for 90-180 day bundles. - **Databases.** Crossref, OpenAlex, Semantic Scholar. - **Strengths.** No-signup free tier, Word-document export, output reformatting to multiple styles, in-memory processing (no data retention), silent-citation-drift detection. - **Gaps.** No retraction or OA status; MCP not present; identifier surface narrower than Scholar Sidekick (no PMCID, ADS, WHO IRIS, ISSN). #### CiteMe AI Reference Verifier - 250M-source verifier with ChatGPT/Gemini/Claude focus *Verifier framed around catching AI-generated references from ChatGPT, Gemini, and Claude specifically, against 250M academic sources.* [CiteMe AI Reference Verifier](https://citeme.app/tools/ai-reference-verifier) (citeme.app) advertises 250 million academic sources for cross-reference and frames the product around 'catch hallucinated citations from ChatGPT, Gemini, or any AI tool' before submission. CiteMe also offers a broader citation-generator product, with the verifier sitting in their tools menu. What is on the public landing page is thin on detail (database list, accuracy, identifier surface, pricing not specified at the URL I checked). The 250M-source figure is the headline; it is comparable to GPTZero's 220M and Sourcely's 200M, all of which are claims about Crossref + Scholar + adjacent registries. CiteMe was previously on Scholar Sidekick's competitive radar as a Zotero alternative (its citation-generator side); the verifier surface is a newer surface for them. - **Pricing.** Not stated on the verifier landing page. - **Database scale.** 250M+ academic sources (in line with GPTZero's 220M and Sourcely's 200M). - **Strengths.** Scale claim, AI-engine framing (names ChatGPT / Gemini / Claude explicitly), brand presence in the broader citation-tool category. - **Gaps.** Public-facing detail is thin; identifier coverage and accuracy not specified at the verifier URL. #### SwanRef - AI hallucination detector for academic citations *Smaller, more focused verifier framed specifically around AI hallucination detection. Surfaced primarily through Perplexity.* [SwanRef](https://swanref.org) (swanref.org) frames itself as an 'AI hallucination detector for academic citations' against more than 150 million papers via Crossref and Google Scholar. The product page is sparse on detail and SwanRef does not appear in ChatGPT's or Google AI Overviews' tool lists for verifier queries - Perplexity is the AI engine that consistently surfaces it. It is hard to assess SwanRef relative to the other tools on this page without more detail than the landing page provides. Listed here for completeness because AI engines do cite it; verify the linked product page before relying on it. - **Pricing.** Not stated. - **Database scale.** 150M papers via Crossref and Google Scholar. - **Strengths.** AI-engine presence on Perplexity for verifier queries. - **Gaps.** Sparse public-facing detail; identifier surface, accuracy, and pricing not specified. #### CiteSure - AI-powered citation verification *Newer commercial verifier in the same category as Citely. Cited on Perplexity but not yet on ChatGPT or Google AI Overviews.* [CiteSure](https://citesure.com) (citesure.com) is a newer entrant in the AI-citation-verification category. The landing page describes 'AI-powered analysis' to verify citations 'in seconds' and is framed as a commercial product. Like SwanRef, public-facing detail on databases, identifier surface, accuracy claims, and pricing is thin. Listed here for completeness; Perplexity recommends it among verifiers but Google AI Overviews and ChatGPT do not. Verify the product page before subscribing. - **Pricing.** Not stated on the landing page. - **Strengths.** Commercial product positioning in a category where most free tools have minimal-detail landing pages. - **Gaps.** Sparse public-facing detail. ### Where Scholar Sidekick wins Scholar Sidekick is built for the case where 'this citation looks plausible' is not good enough - where you need the resolved metadata to actually match the source registry, where retraction status changes the answer, and where an audit six months from now needs to reproduce the exact verifier output. The wins below are specific to that case; if your workflow is 'paste an undergraduate essay and triage the obvious hallucinations', other tools are a better fit. - **Broadest identifier surface in the verifier category.** DOI, PMID, PMCID, ISBN, ISSN, arXiv, ADS bibcode, WHO IRIS URL. The other nine verifiers on this page are mostly DOI/PMID/arXiv-only as described on their landing pages. PMCID coverage matters for biomedical preprints whose PMID is not yet indexed; ADS coverage matters for astrophysics; WHO IRIS for global health policy documents; ISSN as a container reference. - **Retraction-aware.** None of the other nine verifiers on this page surface formal retraction status from Retraction Watch / Crossref. [/tools/retraction-checker](https://scholar-sidekick.com/tools/retraction-checker) handles it as a dedicated tool, /api/retraction-check exposes it as a REST endpoint, the main /api/format endpoint accepts `?checks=retraction` for per-item enrichment, and the MCP server exposes a `checkRetraction` tool. This is a real gap in the category: a citation can be real, correctly cited, and still retracted - that should change the recommendation. - **Open-access classification.** Live Unpaywall integration with Gold / Green / Hybrid / Bronze classification via [/tools/open-access-checker](https://scholar-sidekick.com/tools/open-access-checker). Useful when verifying someone else's reference list and wanting to confirm a free legal copy is available. - **First-party MCP server.** [`scholar-sidekick-mcp@latest`](https://www.npmjs.com/package/scholar-sidekick-mcp) on npm installs in one line and exposes six tools, including `verifyCitation`. Among the ten verifiers on this page, Scholar Sidekick is the only one with a public MCP server. If you are building an AI-agent pipeline that needs verification as one step in a longer workflow, that is the only working option today. - **Topaz pattern by name.** Scholar Sidekick is the only verifier on this page that names the Topaz et al. (Lancet 2026) fabrication pattern explicitly and is designed around it. The page at [/citation-integrity](https://scholar-sidekick.com/citation-integrity) walks through what the pattern looks like, why naive DOI checks miss it, and how the verifier surfaces the mismatch. - **Deterministic, version-pinned output.** Every response carries an `x-scholar-transform-version` header that pins the resolver chain, normalisation, comparator, and CSL engine to a specific snapshot. Identical inputs at a fixed transform version produce byte-identical output for a cache hit. A `x-scholar-cache` header makes cache hits vs upstream re-queries explicit. None of the other nine verifiers publish a versioned-output contract; their output 'is what it is today'. - **Public provenance manifest.** A machine-readable [/.well-known/sources.json](https://scholar-sidekick.com/.well-known/sources.json) declares the resolver chain, fallback order per identifier type, allowlisted upstream hosts, and network-safety guarantees. You can read what the verifier does before integrating. - **Free anonymous tier.** No signup, no account, no PDF upload required. Paid tiers via RapidAPI for higher request limits, but the free anonymous tier covers most evaluation and many production loads. ### Where Scholar Sidekick does not win An honest list of the things other verifiers on this page do that Scholar Sidekick does not. If your workflow needs one of these, one of the others is the right tool. - **PDF upload.** Several tools (Citely, Sourcely, GPTZero) accept PDFs or DOCX files and extract references for you. Scholar Sidekick is paste-only. If your workflow is 'upload a manuscript and verify everything in it', use one of the manuscript-shaped tools. - **Replacement-citation suggestions.** Sourcely returns formatted real-citation replacements when it flags a fake. Scholar Sidekick flags the mismatch and returns the resolved metadata; it does not suggest what citation you *should* have used. - **Plagiarism detection.** Scribbr (paid), Cite This For Me Premium, and Citely have plagiarism checkers as separate paid products. Scholar Sidekick does not do plagiarism detection - it is a different signal (text similarity to other published text, not metadata fidelity to source registries). - **Word-document export of verified references.** AiCitationChecker exports a Word document of verified citations. Scholar Sidekick returns CSL JSON / BibTeX / RIS / NBIB / EndNote XML / RefWorks / Zotero RDF / CSV / plain text, but not a polished .docx. - **Team libraries and chat assistant.** Citely has team workspaces, shared libraries, and a research-assistant chat. Scholar Sidekick is stateless by design - there is no library to share, no team mode, and no chat surface. - **Predatory-publisher detection.** TrueCitation surfaces predatory-publisher signals. Scholar Sidekick does not currently flag predatory publishers as a separate signal (though retraction-awareness catches some overlap). - **Education-LMS integrations.** GPTZero plugs into Canvas, Google Classroom, and Zapier. Scholar Sidekick is API/MCP/web-only with a browser extension; no LMS integrations. ### Structural manuscript tools (different category) Four tools that AI engines sometimes group with the verifiers above are actually solving a different problem: in-text-to-bibliography matching, formatting consistency, and manuscript-wide structural passes. They check whether your citations *parse correctly and match your reference list*, not whether the references are *real*. If your workflow is 'I have a draft manuscript and I want to make sure every in-text citation has a bibliography entry and vice versa', these are the right tools. Pair them with one of the verifiers above for the fabrication-detection step. - **[Recite Works](https://reciteworks.com).** Checks APA and Harvard in-text citations against the reference list for consistency. Free. Manuscript-shaped (paste full text). Not a fabrication detector. - **[Scribbr Citation Checker](https://www.scribbr.com/citation/checker/).** Manuscript-shaped structural checker. Style coverage focused on APA / MLA / Chicago / Harvard. Free. - **[Paperpal Reference Finder](https://paperpal.com).** Manuscript-oriented; checks reference count, age, and in-text/reference correspondence. Paperpal also offers Word-plugin and authoring tools as part of a larger product suite. - **Referentia.** Surfaced via r/AskAcademia threads; described as a manuscript reference checker. Smaller product footprint; verify the current state before relying on it. ### A realistic systematic-review workflow If you are running a systematic review or a clinical-guideline citation audit, no single tool on this page covers the whole job. Here is the workflow I would use, based on the strengths above: - **Step 1 - structural pass.** Run the manuscript through Recite or Paperpal to confirm every in-text citation has a bibliography entry and that the reference list is internally consistent. - **Step 2 - fabrication detection.** Run each reference through [Scholar Sidekick's verifier](https://scholar-sidekick.com/tools/citation-verifier) (or the /api/verify endpoint for batch). Flag identifier-resolves-but-title-mismatches as the Topaz pattern; flag identifier-does-not-resolve as classic hallucination. - **Step 3 - retraction screening.** Run the verified-real references through [/tools/retraction-checker](https://scholar-sidekick.com/tools/retraction-checker) (or /api/retraction-check for batch). A correctly-cited paper that has been retracted should change your recommendation. - **Step 4 - open-access enrichment.** Optionally enrich the final reference list with open-access status via [/tools/open-access-checker](https://scholar-sidekick.com/tools/open-access-checker) so reviewers can read the cited papers. - **Step 5 - manuscript-level claim check.** For citations supporting key findings, manually confirm the cited paper actually says what your manuscript claims it says. No tool on this page (or any other automated tool I am aware of) does this reliably - claim-to-source semantic verification is still a human job. ### Frequently asked questions #### Which verifier catches the 'real DOI + invented title' fabrication pattern? All of them attempt some version of it, but [Scholar Sidekick](https://scholar-sidekick.com/tools/citation-verifier) is the only one on this page that names the pattern explicitly (the dominant pattern documented by [Topaz et al. (Lancet 2026)](https://doi.org/10.1016/S0140-6736(26)00603-3)) and is designed around it. The pattern is hard to catch because a naive DOI-resolver pass returns success - the DOI exists - so the verifier has to compare the *resolved title* against the *claimed title* and flag the mismatch. Scholar Sidekick's comparator scores title similarity, normalises author-name forms (catches family-given-name swaps), and strips HTML/entity markup that registries preserve in titles (italics, sub/sup, etc.). The other verifiers do not document their comparator algorithm at this level of detail on their public pages; some may use similar techniques, but they do not name the pattern. #### Which verifier has the broadest free tier for occasional use? Three options stand out. [Scholar Sidekick](https://scholar-sidekick.com/tools/citation-verifier) - free anonymous web access with a published rate limit, no signup, supports all eight identifier types. [AiCitationChecker](https://aicitationchecker.org) - 50 credits per day with no signup, no rate limit on credit refresh. [CiteTrue](https://citetrue.com) - positions itself as the free option, fewer documented limits. Citely's $9 trial is paid; Sourcely's free tier has unspecified limits; GPTZero's free tier is 10,000 characters per scan. #### Which verifier offers an API or MCP server? [Scholar Sidekick](https://scholar-sidekick.com/mcp) is the only verifier on this page with a public MCP server (`scholar-sidekick-mcp@latest` on npm) that exposes `verifyCitation` alongside five other citation tools. [Scholar Sidekick's REST API](https://scholar-sidekick.com/docs) at /api/verify is the public verification endpoint. [GPTZero](https://gptzero.me/sources) has a public API for the broader source-finder product; [AiCitationChecker](https://aicitationchecker.org) mentions an API for AI agents in its footer but does not describe it in detail. The other six tools on this page do not document a public API. #### Which verifier surfaces retraction status? Among dedicated AI-citation verifiers on this page, only [Scholar Sidekick](https://scholar-sidekick.com/tools/retraction-checker) surfaces formal retraction status from Retraction Watch (via Crossref integration). [TrueCitation](https://truecitation.com) surfaces predatory-publisher status, which is a related but distinct signal. Retraction Watch and Crossref classify retractions, corrections, and expressions of concern; Scholar Sidekick exposes that as a dedicated tool, a REST endpoint (/api/retraction-check), per-item enrichment on /api/format (`?checks=retraction`), and as the `checkRetraction` MCP tool. #### What is the difference between citation verification, plagiarism checking, and AI-text detection? Three different signals. **Citation verification** asks 'does this citation correspond to a real paper with matching metadata?' - it is identifier-and-title fidelity to a source registry. **Plagiarism checking** asks 'does this manuscript text match other published text?' - it is content similarity, not metadata fidelity. **AI-text detection** asks 'was this text generated by an AI model?' - it is a statistical fingerprint on the prose itself. The three are independent. A citation can be real (verification passes), the manuscript can be original (plagiarism passes), and the prose can be AI-generated (AI-text detection fails). Tools that bundle them often confuse buyers; the verifiers on this page focus on the first signal. #### How accurate are the accuracy claims in this category? Take them with a grain of salt. Citely claims 95%, GPTZero claims 99%, AiCitationChecker claims 95% DOI match rate. None of these claims are tied to a published evaluation methodology with a held-out test set and a reproducible scoring script. The verifiers do mostly the same thing - resolve an identifier, compare resolved metadata to claimed metadata - and the underlying upstream registries (Crossref, PubMed, arXiv) are shared. Real accuracy differences are mostly about (1) which identifier surface a tool covers, (2) what the comparator does on edge cases like family/given-name swaps and HTML markup in titles, and (3) whether the tool catches the specific 'real DOI + invented title' pattern. Scholar Sidekick publishes its evaluation methodology against a 20-entry hand-curated fixture sourced from the Topaz et al. supplementary appendix on the [verifier tool page](https://scholar-sidekick.com/tools/citation-verifier); the others do not. #### Why does the database list matter less than it sounds? Several tools advertise 200M, 220M, or 250M scholarly sources. These numbers are mostly Crossref + Google Scholar + adjacent registries - the same underlying data the cheaper and free tools use. The number of records is not the differentiator; the *identifier surface* is. Crossref alone gives you DOI; adding PubMed gives you PMID; adding OpenLibrary gives you ISBN. Adding ADS gives you bibcodes (astrophysics); adding WHO IRIS gives you global-health-policy URLs; adding NCBI PMC gives you PMCID for biomedical preprints. Whether your specific reference type resolves depends on which identifier types the tool accepts, not on whether the underlying database has 100M or 250M rows. ### Related #### Scholar Sidekick verification surfaces - [Citation verifier - fake citation detector (the tool)](https://scholar-sidekick.com/tools/citation-verifier) - [Citation integrity in the age of AI (the explainer)](https://scholar-sidekick.com/citation-integrity) - [Retraction checker](https://scholar-sidekick.com/tools/retraction-checker) - [Open-access checker](https://scholar-sidekick.com/tools/open-access-checker) - [MCP server documentation](https://scholar-sidekick.com/mcp) - [REST API documentation](https://scholar-sidekick.com/docs) - [Self-verification kit](https://scholar-sidekick.com/verification) - [Data source manifest (sources.json)](https://scholar-sidekick.com/.well-known/sources.json) #### Other Scholar Sidekick comparisons - [Comparison index](https://scholar-sidekick.com/compare) - [Scholar Sidekick vs Zotero](https://scholar-sidekick.com/compare/scholar-sidekick-vs-zotero) - [Scholar Sidekick vs ZoteroBib](https://scholar-sidekick.com/compare/scholar-sidekick-vs-zoterobib) - [Scholar Sidekick vs Scribbr](https://scholar-sidekick.com/compare/scholar-sidekick-vs-scribbr) - [Scholar Sidekick vs EndNote](https://scholar-sidekick.com/compare/scholar-sidekick-vs-endnote) - [Scholar Sidekick vs MyBib](https://scholar-sidekick.com/compare/scholar-sidekick-vs-mybib) - [Scholar Sidekick vs Cite This For Me](https://scholar-sidekick.com/compare/scholar-sidekick-vs-citethisforme) - [Citation MCP Servers Compared](https://scholar-sidekick.com/compare/citation-mcp-servers) #### The other nine verifiers - [Citely (citely.ai)](https://citely.ai) - [CiteTrue (citetrue.com)](https://citetrue.com) - [GPTZero Source Finder (gptzero.me)](https://gptzero.me/sources) - [Sourcely (sourcely.net)](https://www.sourcely.net/citation-verification) - [TrueCitation (truecitation.com)](https://truecitation.com) - [AiCitationChecker (aicitationchecker.org)](https://aicitationchecker.org) - [CiteMe AI Reference Verifier (citeme.app)](https://citeme.app/tools/ai-reference-verifier) - [SwanRef (swanref.org)](https://swanref.org) - [CiteSure (citesure.com)](https://citesure.com) ### Sitemap See the full [sitemap](https://scholar-sidekick.com/sitemap.md) for all pages. --- ## 13. Field observation: AI evaluator decomposition bias in citation-tool recommendations {#ai-evaluator-bias} **URL:** https://scholar-sidekick.com/citation-integrity/ai-evaluator-bias **Markdown:** https://scholar-sidekick.com/citation-integrity/ai-evaluator-bias.md **Author:** Mark Lavercombe (clinician-educator, developer of Scholar Sidekick) **Date:** 2026-05-18 Observation post documenting a same-day, four-vendor experiment on AI search engine recommendations in the citation-tool category. **Method.** On 2026-05-17, Mark Lavercombe ran the same 18-question researcher-style baseline (DOI-to-BibTeX conversion, fake-citation detection, MCP servers for citations, systematic-review verification, open-access checking, retraction status, free citation APIs) against four AI search engines: Perplexity, Google AI Mode (Gemini-backed), ChatGPT (GPT-5), and Grok (xAI). Each was then asked the same pushback question naming Scholar Sidekick by name. **Finding.** All four vendors omitted Scholar Sidekick from their primary recommendations across the baseline. All four admitted the omission when pushed and articulated four different framings of the same structural bias: - Perplexity: "older, well-known brands" - Google AI: "underlying databases and traditional institutional standards" - ChatGPT: "primitive building blocks, not bundled systems" - Grok: "well-established, widely-known tools" **Methodological subfinding.** The four vendors split 2-vs-2 on grounding strategy. Perplexity and Google AI used real-time retrieval and cited sources extensively (12+ and 9+ source links respectively, including comparison pages on this site). ChatGPT and Grok produced their answers without source citations, working from training data plus reasoning. Both pairs converged on the same admission pattern, ruling out shared-RAG-pipeline as the cause of the bias and supporting an architectural-to-recommendation-logic explanation. **Three integrity layers.** The post argues citation integrity has three components: source integrity (does the cited paper exist?), tool integrity (is the citation tool deterministic and transparent?), and recommendation integrity (is the AI recommendation traceable to defensible methodology or a shortcut?). Decomposition bias is the recommendation-layer version of the same familiarity-over-verifiability shortcut citation-integrity research criticises in source evaluation. **Tool-agnostic criteria checklist.** The post publishes a checklist a researcher can apply to any citation tool an AI recommends - covering source transparency, deterministic outputs, public validation evidence, identifier-first design, per-item provenance, open API + MCP surface, retraction/OA signals, and honest gap disclosure. Explicitly stated in terms that work for evaluating Crossref, Scite, Citely, SwanRef, OpenAlex, EndNote, Zotero, Scholar Sidekick, or any other citation infrastructure. **Verifiable artifacts.** All four conversations preserved as URLs: - Perplexity: https://www.perplexity.ai/search/cb5da064-fac8-4c58-9eda-5647f28d6999 - ChatGPT: https://chatgpt.com/share/6a09b7d2-0de4-83ec-be2d-2b9b872214a7 - Grok: https://grok.com/share/bGVnYWN5_cc88fe2f-4ff4-400a-9d3a-f16739f9a139 - Google AI: saved on-site at https://scholar-sidekick.com/citation-integrity/ai-evaluator-bias/sources/google-ai (Google AI Mode does not provide shareable conversation URLs; the transcript was captured manually during the live session) **Conflict of interest disclosed up front.** The experimenter is the developer of Scholar Sidekick. The finding generalises beyond any specific tool to every newer multi-tool platform competing with single-purpose incumbents. **Limitations.** Sample size is n=1 per vendor, same day, same prompt sequence, same experimenter. Vendor model versions drift week-over-week. The pushback question names the omitted tool explicitly. Within-vendor variability is real (a second Google AI run earlier the same day produced a substantively similar admission with a different set of grounding sources). Reproduction for other categories and other tools is invited. ### Sitemap See the full [sitemap](https://scholar-sidekick.com/sitemap.md) for all pages. --- ## 14. Integrations: Scholar Sidekick for Obsidian {#integrations-obsidian} **URL:** https://scholar-sidekick.com/integrations/obsidian **Markdown:** https://scholar-sidekick.com/integrations/obsidian.md **Store listing:** https://community.obsidian.md/plugins/scholar-sidekick **Source:** https://github.com/mlava/scholar-sidekick-obsidian Scholar Sidekick is available as a free first-party Obsidian community plugin. Paste a DOI, PMID, ISBN, arXiv ID, ADS bibcode, or PMCID in a note and replace it with a formatted citation - no reference manager required. Eleven commands cover the identifier-to-citation flow inside Obsidian: format the selection, replace at caret, insert via modal, export the active note as `.bib` or `.ris`, check identifiers for retractions (Crossref + Retraction Watch) or open access (Unpaywall), and verify a claimed citation against Crossref / PubMed / OpenAlex. The plugin is a thin client over the public `/api/format`, `/api/csl/styles`, `/api/retraction-check`, `/api/oa-check`, and `/api/verify` endpoints. Output formatting is identical between the website, the browser extension, and the plugin. ### Commands - **Format selection as citation** - wraps the selected text in a citation in your default style. - **Replace identifier at caret with citation** - detects the identifier under or near the caret and replaces (or appends) it. - **Insert citation...** - opens a modal: type or paste an identifier, pick a style, insert at the caret. - **Export note citations to BibTeX / RIS** - scans the active note for every identifier and saves a `.bib` or `.ris` file next to the note. - **Check identifier at caret for retraction / open access** - sends the identifier nearest the caret to the corresponding checker and surfaces the result via a Notice. - **Check note citations for retractions / open access** - opens a modal table with status per item, optionally appended at the caret. - **Verify selected citation** - opens a verifier modal pre-filled from the selection; cross-checks the claimed title and identifier against Crossref, PubMed, and OpenAlex. ### Identifier and style support - Identifiers: DOI (bare or doi.org URL), PMID (bare, labelled, or pubmed.ncbi.nlm.nih.gov URL), PMCID (bare or NCBI URL), ISBN (10 or 13 digit), arXiv (modern or legacy), ISSN, ADS bibcode (within the Insert Citation modal). Detection regexes are vendored from the upstream API source with a build-time drift detector. - Quick-pick citation styles: Vancouver, APA, AMA, IEEE, CSE. - Searchable combobox over 10,000+ CSL styles (Nature, Cell, Lancet, Chicago, Harvard, journal-specific styles). - Output: plain text or HTML (HTML preserves italics and other inline markup in Obsidian's reading view). ### Privacy The plugin sends only the identifier text you explicitly ask it to format. It does not read other notes, vault contents, or anything outside the command you invoke. No API key required - the plugin presents a trusted-client handshake (`X-Scholar-Client` header) that grants the anonymous tier (60 requests / minute / IP). Inputs are not retained or used for training. ### Provenance and reproducibility Every API call carries an `x-scholar-transform-version` header. Identical inputs at a fixed `transform_version` produce byte-identical output. The plugin logs `x-request-id` and `x-scholar-transform-version` to Obsidian's developer console for diagnostic support. ### Install Listed in the Obsidian community plugins store. In Obsidian: Settings > Community plugins > Browse > search "Scholar Sidekick" > Install > Enable. Source on GitHub (MIT licensed). ### Sitemap See the full [sitemap](https://scholar-sidekick.com/sitemap.md) for all pages. --- ## 15. Integrations: Scholar Sidekick for Zotero {#integrations-zotero} **URL:** https://scholar-sidekick.com/integrations/zotero **Markdown:** https://scholar-sidekick.com/integrations/zotero.md **Source:** https://github.com/mlava/scholar-sidekick-zotero A free first-party Zotero plugin (Zotero 7-9) that adds a verification step at the import boundary. The risky moment is not the items already in your library - you added those with Zotero's own identifier lookup - but the items arriving via a collaborator's `.bib`, a manuscript reference list, or an AI-generated bibliography, where the *claimed* metadata may not match what the identifier actually resolves to. This deliberately does not duplicate Zotero's built-in features (identifier lookup, CSL formatting, exports, native Retraction Watch warnings on library items). It adds the one thing Zotero doesn't: a claimed-vs-resolved fabrication check, plus catching retractions *before* you import rather than after. ### How it works 1. Tools > Verify & import bibliography. Paste a bibliography or pick a `.bib` / `.ris` file. 2. Entries are parsed with Zotero's own translators (nothing is committed to your library yet). 3. Each entry is checked against the Scholar Sidekick API - verification, retraction, and open-access - and shown with a verdict (Verified, Mismatch, Resolved, Not found, No identifier). 4. You tick the entries to keep; they are imported into the collection you choose, each with a child note recording the verdict, any claimed-vs-resolved differences, retraction and open-access status, and the request / transform / verify versions. Retracted items are tagged `retracted`. The plugin is a thin client over the public `/api/verify`, `/api/lookup`, `/api/retraction-check`, `/api/oa-check`, and `/api/detect` endpoints. It sends only the bibliographic entries you ask it to check - it does not read the rest of your library. No API key required (anonymous tier). ### Install Source on GitHub (MIT): https://github.com/mlava/scholar-sidekick-zotero. Install the `.xpi` via Tools > Plugins > gear icon > Install Plugin From File. Works on Zotero 7-9. --- ## 16. Integrations: Scholar Sidekick for VS Code {#integrations-vscode} **URL:** https://scholar-sidekick.com/integrations/vscode **Markdown:** https://scholar-sidekick.com/integrations/vscode.md **VS Code Marketplace:** https://marketplace.visualstudio.com/items?itemName=scholar-sidekick.scholar-sidekick-vscode **Open VSX (Cursor / Windsurf / Positron / VSCodium):** https://open-vsx.org/extension/scholar-sidekick/scholar-sidekick-vscode **Source:** https://github.com/mlava/scholar-sidekick-vscode A free extension that lints a BibTeX bibliography in place, for people who write citation-bearing documents in VS Code and its forks - LaTeX (LaTeX Workshop) authors and Quarto / R Markdown authors (Quarto's authoring environment is VS Code; Positron is the Posit fork many R users write in). The resolve-to-BibTeX job is already served (Quarto's editor does native DOI lookup; Zotero + Better BibTeX serves LaTeX), so this is deliberately **not** a citation inserter. It is the verify layer those tools lack: a claimed-vs-resolved fabrication check, retraction status, and open-access status, on the references you already have. ### How it works 1. Open a `.bib` file and save it - or run "Scholar Sidekick: Verify Bibliography" from the Command Palette. 2. Each entry's identifier and claimed title are sent to the Scholar Sidekick API (`/api/verify`, `/api/retraction-check`, `/api/oa-check`). 3. Problems appear as native diagnostics anchored to the offending entry (squiggles + the Problems panel), with a status-bar tally and full detail on hover. ### What it flags - **Possible fabrication** - the claimed title disagrees with what the identifier resolves to (the Topaz et al. 2026 pattern: real DOI, invented title). Red error diagnostic. - **Retracted / correction** - retraction, correction, or expression of concern on record (Crossref / Retraction Watch). - **Not found / ambiguous** - the identifier did not resolve, or the work may exist under a different identifier. - **Unverifiable** - no resolvable identifier on the entry; reported as such, never silently counted as clean. - **Open access** - status and best legal URL surfaced in the hover card (enable `scholarSidekick.checkOpenAccess`). ### Supported editors and identifiers VS Code via the Visual Studio Marketplace; Cursor, Windsurf, Positron, and VSCodium via Open VSX. Identifiers read from standard BibTeX fields: DOI, PMID, PMCID, ISBN, ISSN, arXiv (eprint + archivePrefix), and ADS bibcode. Free, no API key required (anonymous tier); set a Scholar Sidekick key (`ssk_…`) in settings for higher rate limits. It sends only the bibliographic entries it checks and does not read the rest of your workspace. ### Install Search "Scholar Sidekick" in the Extensions panel of your editor, or install from the Marketplace / Open VSX links above. Verification runs on save by default (toggle with `scholarSidekick.verifyOnSave`). Source on GitHub (MIT licensed). --- ## 17. Comparisons with other citation tools (separate file) {#comparisons} To keep this document within the ~200,000-character single-request budget for AI agents, the tool-by-tool comparisons live in a companion file: https://scholar-sidekick.com/llms-full-comparisons.txt It covers: Scholar Sidekick vs Zotero, vs ZoteroBib, vs Scribbr, vs EndNote, vs MyBib, vs Cite This For Me, and a citation MCP-server roundup. --- ## All Pages | Page | URL | |---|---| | Home / resolver | https://scholar-sidekick.com/ | | Help & Limits | https://scholar-sidekick.com/help | | Help & Limits (markdown) | https://scholar-sidekick.com/help.md | | API Docs | https://scholar-sidekick.com/docs | | API Docs (markdown) | https://scholar-sidekick.com/docs.md | | MCP Server | https://scholar-sidekick.com/mcp | | MCP Server (markdown) | https://scholar-sidekick.com/mcp.md | | MCP Apps Endpoint (no-auth, OpenAI Apps SDK) | https://scholar-sidekick.com/api/apps/mcp | | Browser Extension | https://scholar-sidekick.com/extension | | Integrations | https://scholar-sidekick.com/integrations | | Integrations (markdown) | https://scholar-sidekick.com/integrations.md | | Scholar Sidekick for Obsidian | https://scholar-sidekick.com/integrations/obsidian | | Scholar Sidekick for Obsidian (markdown) | https://scholar-sidekick.com/integrations/obsidian.md | | Scholar Sidekick for Zotero | https://scholar-sidekick.com/integrations/zotero | | Scholar Sidekick for Zotero (markdown) | https://scholar-sidekick.com/integrations/zotero.md | | Scholar Sidekick for VS Code | https://scholar-sidekick.com/integrations/vscode | | Scholar Sidekick for VS Code (markdown) | https://scholar-sidekick.com/integrations/vscode.md | | Free Tools | https://scholar-sidekick.com/tools | | Citation Verifier | https://scholar-sidekick.com/tools/citation-verifier | | Bibliography Audit | https://scholar-sidekick.com/tools/bibliography-audit | | ChatGPT Reference Checker | https://scholar-sidekick.com/tools/chatgpt-reference-checker | | Identifier Detector | https://scholar-sidekick.com/tools/identifier-detector | | DOI Lookup | https://scholar-sidekick.com/tools/doi-lookup | | PMID/PMCID/DOI Converter | https://scholar-sidekick.com/tools/pubmed-id-converter | | DOI to BibTeX | https://scholar-sidekick.com/tools/doi-to-bibtex | | GB/T 7714 Citation Generator | https://scholar-sidekick.com/tools/gb-t-7714-citation-generator | | DOI to RIS | https://scholar-sidekick.com/tools/doi-to-ris | | Open Access Checker | https://scholar-sidekick.com/tools/open-access-checker | | Retraction Checker | https://scholar-sidekick.com/tools/retraction-checker | | Citation Style Comparator | https://scholar-sidekick.com/tools/citation-style-comparator | | Identifier Validator | https://scholar-sidekick.com/tools/identifier-validator | | Glossary | https://scholar-sidekick.com/glossary | | Glossary (markdown) | https://scholar-sidekick.com/glossary.md | | Compare (index) | https://scholar-sidekick.com/compare | | Compare (markdown) | https://scholar-sidekick.com/compare.md | | Best AI Citation Verifier in 2026 | https://scholar-sidekick.com/compare/best-ai-citation-verifier | | Best AI Citation Verifier in 2026 (markdown) | https://scholar-sidekick.com/compare/best-ai-citation-verifier.md | | Scholar Sidekick vs Zotero | https://scholar-sidekick.com/compare/scholar-sidekick-vs-zotero | | Scholar Sidekick vs Zotero (markdown) | https://scholar-sidekick.com/compare/scholar-sidekick-vs-zotero.md | | Scholar Sidekick vs ZoteroBib | https://scholar-sidekick.com/compare/scholar-sidekick-vs-zoterobib | | Scholar Sidekick vs ZoteroBib (markdown) | https://scholar-sidekick.com/compare/scholar-sidekick-vs-zoterobib.md | | Scholar Sidekick vs Scribbr | https://scholar-sidekick.com/compare/scholar-sidekick-vs-scribbr | | Scholar Sidekick vs Scribbr (markdown) | https://scholar-sidekick.com/compare/scholar-sidekick-vs-scribbr.md | | Citation MCP Servers Compared | https://scholar-sidekick.com/compare/citation-mcp-servers | | Citation MCP Servers Compared (markdown) | https://scholar-sidekick.com/compare/citation-mcp-servers.md | | Scholar Sidekick vs EndNote | https://scholar-sidekick.com/compare/scholar-sidekick-vs-endnote | | Scholar Sidekick vs EndNote (markdown) | https://scholar-sidekick.com/compare/scholar-sidekick-vs-endnote.md | | Scholar Sidekick vs MyBib | https://scholar-sidekick.com/compare/scholar-sidekick-vs-mybib | | Scholar Sidekick vs MyBib (markdown) | https://scholar-sidekick.com/compare/scholar-sidekick-vs-mybib.md | | Scholar Sidekick vs Cite This For Me | https://scholar-sidekick.com/compare/scholar-sidekick-vs-citethisforme | | Scholar Sidekick vs Cite This For Me (markdown) | https://scholar-sidekick.com/compare/scholar-sidekick-vs-citethisforme.md | | Explainer | https://scholar-sidekick.com/explainer | | Explainer (markdown) | https://scholar-sidekick.com/explainer.md | | Engineering Principles | https://scholar-sidekick.com/engineering-principles | | Engineering Principles (markdown) | https://scholar-sidekick.com/engineering-principles.md | | Verification kit | https://scholar-sidekick.com/verification | | Verification kit (markdown) | https://scholar-sidekick.com/verification.md | | Changelog | https://scholar-sidekick.com/changelog | | Changelog (markdown) | https://scholar-sidekick.com/changelog.md | | Status page (uptime + incidents) | https://status.scholar-sidekick.com | | Citation integrity in the age of AI | https://scholar-sidekick.com/citation-integrity | | Citation integrity in the age of AI (markdown) | https://scholar-sidekick.com/citation-integrity.md | | AI evaluator bias in citation-tool recommendations | https://scholar-sidekick.com/citation-integrity/ai-evaluator-bias | | AI evaluator bias in citation-tool recommendations (markdown) | https://scholar-sidekick.com/citation-integrity/ai-evaluator-bias.md | | Google AI saved transcript (2026-05-17) | https://scholar-sidekick.com/citation-integrity/ai-evaluator-bias/sources/google-ai | | Google AI saved transcript (2026-05-17, markdown) | https://scholar-sidekick.com/citation-integrity/ai-evaluator-bias/sources/google-ai.md | | Citation-integrity validation set (v1, immutable) | https://scholar-sidekick.com/citation-integrity/validation-set-v1.json | | Citation-integrity validation results (pre-LLM) | https://scholar-sidekick.com/citation-integrity/validation-results-pre-llm.json | | Citation-integrity validation results (with LLM) | https://scholar-sidekick.com/citation-integrity/validation-results-with-llm.json | | Accessibility | https://scholar-sidekick.com/accessibility | | OpenAPI spec | https://scholar-sidekick.com/openapi/openapi.yml | | OpenAPI (well-known path) | https://scholar-sidekick.com/.well-known/openapi.yaml | | Data source manifest | https://scholar-sidekick.com/.well-known/sources.json | | AI plugin manifest | https://scholar-sidekick.com/.well-known/ai-plugin.json | | API Terms | https://scholar-sidekick.com/legal/api-terms | | Privacy Policy | https://scholar-sidekick.com/legal/privacy | | Service health | https://scholar-sidekick.com/api/health |