Unpaywall Has a Free API — Find Open Access Versions of Any Paywalled Paper

You find the perfect paper for your research. You click the link. And you hit a $40 paywall. But what if that same paper is legally available for free somewhere else? Unpaywall checks 50,000+ open-access sources to find free legal copies of paywalled papers. It covers 30M+ articles. And it has a free API. How It Works Give Unpaywall a DOI, and it tells you: Is there a free legal version? Where is it hosted? (university repo, preprint server, author page) What type of open access? (gold, green, hybrid, bronze) Quick Start import requests def find_free_version ( doi , email ): resp = requests . get ( f " https://api.unpaywall.org/v2/ { doi } " , params = { " email " : email }) data = resp . json () if data . get ( " is_oa " ): best = data . get ( " best_oa_location " , {}) print ( f " FREE version found! " ) print ( f " URL: { best . get ( ' url_for_pdf ' ) or best . get ( ' url ' ) } " ) print ( f " Host: { best . get ( ' host_type ' ) } ( { best . get ( ' repository_institution ' , ' N