Unpaywall is a free browser extension and API that finds legal, free-to-read copies of paywalled research papers. It suits students, researchers and libraries, and the extension and API cost nothing. The OpenAlex team maintains it and says it is not being retired.
Unpaywall now runs on OpenAlex
Unpaywall moved onto the OpenAlex database in late 2025 and is maintained by the OpenAlex team. Its help center says the DOI lookup API, browser extension and Data Feed are unchanged and staying.
The article search on unpaywall.org has been retired. To search for papers by topic, the team points users to OpenAlex.
Checked October 4, 2026
The bottom line
Install it if you read research papers; it is free and legal.
7.7
Our score
7.7 / 10
Conversion Gems editorial verdict
Free extension and API
Features6/10
6 - extension, free DOI API, 1,000-DOI bulk tool and Data Feed; article search retired.
Value10/10
10 - extension and API are free; only the institutional Data Feed is paid.
Ease of use9/10
9 - install the extension and a green tab appears on article pages, no account needed.
Ecosystem7/10
7 - public API plus link resolver integrations with SFX, EBSCO and 360 Link; Crossref DOIs only.
Support5/10
5 - FAQ and OpenAlex help center docs; no live help found for free users.
What it really is
A free browser extension and API that find legal open-access copies of scholarly articles.
Our take
Unpaywall does one job well: when you land on a paywalled paper, it tells you if a legal free copy exists and links to it. Its data now runs on OpenAlex, and the team says the extension and API are staying, which matters after the article search was retired. The extensions themselves have not been updated in a while, January 2025 on Chrome and 2021 on Firefox, so expect a plain tool rather than new features. It cannot conjure a copy that no one has posted.
Why we rate it
It gives anyone a free, legal route to millions of open-access papers in one click.
The catch
It only finds copies that exist, and the extensions see infrequent updates.
Best for
Students and researchers hitting paywalls
Libraries adding open-access links
Developers checking open-access status by DOI
Not good for
Papers with no free version anywhere
Searching for papers by topic (use OpenAlex)
Non-DOI content
Friction report
Time to value
Instant: install the extension and open any article page.
Scale breakpoint
Bulk data needs move you to the paid Data Feed or the OpenAlex API.
Walled garden
None: open data and an MIT-licensed Firefox add-on.
Unpaywall products and cost
Product
What it does
Cost
Browser extension
Green tab on article pages when a legal free copy exists (Chrome; Firefox desktop and Android)
Free
REST API
Open-access status and best location for any Crossref DOI
Free
Simple Query Tool
Checks up to 1,000 DOIs and emails the results
Free
Data Feed
Daily change files in the Unpaywall record format
Subscription (price not published)
From Unpaywall's product pages and the OpenAlex help center, checked 4 October 2026.
Frequently Asked Questions
Yes. The browser extension and the DOI lookup API are free. Only the Data Feed, which delivers daily data updates to institutions, is a subscription (checked 4 October 2026).
Yes. It links only to copies that are free to read legally, such as author-posted manuscripts on university and government servers, a practice known as Green Open Access. It does not bypass paywalls.
No. The OpenAlex team, which maintains it, says it is not retiring Unpaywall and that the API, extension and Data Feed are staying. Only the article search on unpaywall.org was retired, with OpenAlex recommended instead.
The Firefox add-on supports Firefox for Android. The Chrome extension is for desktop Chrome.
When you open a scholarly article, it checks its database for a free legal copy. If one exists, a green tab appears on the side of the page that links to the full text.
For searching papers, the Unpaywall team points to OpenAlex. In our directory, Perplexity helps with cited answers, and Paper Digest and Afforai help you read and summarise papers once you have them.
Unpaywall alternatives
Other research tools in our directory:
Perplexity.ai: AI search that answers questions with linked sources.
Paper Digest: Summarises research papers and articles so you can skim them faster.
Afforai: AI research assistant for chatting with PDFs and searching academic literature.
