---
title: DOI Lookup - Verify & Retrieve Paper Metadata | Scholar Sidekick
description: Enter a DOI, PMID, or scholarly identifier to verify and retrieve full metadata: title, authors, journal, year, and more. Free, no signup.
doc_version: "1.0"
last_updated: "2026-05-18"
---

# DOI Lookup

> HTML version: https://scholar-sidekick.com/tools/doi-lookup

Paste a DOI (or PMID, PMCID, ISBN, arXiv ID, ISSN, ADS bibcode, or scholarly URL) and see the full metadata the publisher has on file: title, authors, journal or container, year, volume, issue, pages, language, type, and identifier links.

## What this tool does

Resolves the identifier against the authoritative registry it belongs to (Crossref for DOIs, PubMed for PMIDs, OpenLibrary for ISBNs, arXiv for preprints, ADS for astrophysics, WHO IRIS for grey literature) and renders the structured metadata. The same data backs every other Scholar Sidekick tool, so what you see here is what gets formatted into a citation or exported into BibTeX / RIS elsewhere on the site.

## How to use

1. Open [the tool](https://scholar-sidekick.com/tools/doi-lookup).
2. Paste the identifier.
3. Inspect the resolved metadata. Click through to the publisher landing page from the DOI link.

## Programmatic access

The same lookup is exposed via the [`POST /api/format`](https://scholar-sidekick.com/docs) endpoint (raw metadata is in the response payload) and the [scholar-sidekick MCP](https://scholar-sidekick.com/mcp) `resolveIdentifier` tool. Anonymous access is free with a published rate limit.

## Related tools

- [Identifier Validator](https://scholar-sidekick.com/tools/identifier-validator) - single ID well-formedness and resolvability check (no metadata fetch)
- [Identifier Detector](https://scholar-sidekick.com/tools/identifier-detector) - extract all identifiers from a block of text
- [Citation Verifier](https://scholar-sidekick.com/tools/citation-verifier) - check that a claimed citation matches the paper at its identifier
- [Free tools index](https://scholar-sidekick.com/tools) - all citation tools

## Sitemap

See the full [sitemap](https://scholar-sidekick.com/sitemap.md) for all pages.