This Rest API provides a way to access resources with multiple formats in Open Library. To request any content, the requested format can be specified using Accept: header or as part of the URL. The currently available formats are JSON and RDF. Open Library has developed a suite of APIs to help developers get up and running with the provided reference data. They lend ebooks worldwide, and have over two million free ebooks available and 250,000 more in the lending library, where there is a web page for every book.