This API allows you to turn book identifier information (ISBN, LCCN etc.) into direct links to Open Library's online-readable or borrowable books from the Open Library lending program. Returned items may include readable matches for different editions of the same work and information from the Data API including all Open Library data about a book. It is used to request information on one or more books using library identifiers such as; ISBNs, OCLC Numbers, LCCNs and OLIDs (Open Library Identifiers). Requests can be made in formats of single and multiple. 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.