Work: The OpenAccess object | OpenAlex documentation

"...The OpenAccess object The OpenAccess object describes access options for a given work. It's only found as part of the Work object. is_oa Boolean: True if this work is Open Access (OA).  There are many ways to define OA. OpenAlex uses a broad definition: having a URL where you can read the fulltext of this work without needing to pay money or log in. You can use the  alternate_host_venues and oa_status fields to narrow your results further, accommodating any definition of OA you like. is_oa: true oa_status String: The Open Access (OA) status of this work. Possible values are: gold: Published in an OA journal that is indexed by the DOAJ green: Toll-access on the publisher landing page, but there is a free copy in an OA repository. hybrid: Free under an open license in a toll-access journal. bronze: Free to read on the publisher landing page, but without any identifiable license. closed: All other articles. oa_status: "gold" oa_url String: The best Open Access (OA) URL for this work.  Although there are many ways to define OA, in this context an OA URL is one where you can read the fulltext of this work without needing to pay money or log in. The "best" such URL is the one closest to the version of record.  This URL might be a direct link to a PDF, or it might be to a landing page that links to the free PDF oa_url: "https://peerj.com/articles/4375.pdf"" ​