---
title: Open Access Checker - Is This Paper Free? | Scholar Sidekick
description: 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.
doc_version: "1.0"
last_updated: "2026-05-18"
---

# Open Access Checker

> HTML version: https://scholar-sidekick.com/tools/open-access-checker

Enter a DOI, PMID, or arXiv ID and see whether the paper is openly accessible - and if so, where to read the legal free copy. Powered by [Unpaywall](https://unpaywall.org/).

## What this tool does

Cross-references the identifier with Unpaywall's open-access index and returns the best legal free copy available - publisher gold OA, hybrid OA, green-OA repository deposit, or preprint server version - plus the OA status (`gold`, `hybrid`, `green`, `bronze`, or `closed`), the license, and the version (published / accepted / submitted).

## How to use

1. Open [the tool](https://scholar-sidekick.com/tools/open-access-checker).
2. Paste the identifier.
3. If a legal free copy exists, click through to read it.

## Programmatic access

OA enrichment is available through the [`POST /api/oa-check`](https://scholar-sidekick.com/docs) endpoint and the [scholar-sidekick MCP](https://scholar-sidekick.com/mcp) `checkOpenAccess` tool. Anonymous access is free with a published rate limit.

## Related tools

- [Retraction Checker](https://scholar-sidekick.com/tools/retraction-checker) - the integrity counterpart: has the paper been retracted, corrected, or flagged?
- [DOI Lookup](https://scholar-sidekick.com/tools/doi-lookup) - full metadata for a single identifier
- [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.