scholarly-metadata
Unpaywall
A database that maps DOIs to legal open-access copies of papers, tracking OA status for around 150 million DOIs. Give it a DOI and it reports whether a free, legitimate full-text copy exists and where, via a simple free API. The standard way to answer 'can I read this paywalled paper for free somewhere legitimate?'
Son utilité et son fonctionnement
Reach for Unpaywall when you want to know whether a specific paper is available legally for free somewhere on the web. Give it any DOI and it searches more than 50,000 open-access sources, including repositories, preprint servers, and publisher OA pages, to tell you whether a free full-text copy exists and where. The lookup is instant via a free API that requires no registration, just your email address as a parameter. It is the fastest way to answer the question: is there a legitimate free version of this paywalled article?
Ce qu’elle contient
Tracks open-access status for a number of DOIs comparable to the Crossref registry, currently in the range of roughly 150 to 180 million DOIs, with around a quarter of Crossref DOIs finding at least one free legal copy.
Accès API
https://api.unpaywall.org/v2/ <doi>?email=<email>
Accès
Programmatic API access (a key may be required, see the API tag).