The Internet Archive and Open Library offers over 10,000,000 fully accessible books and texts. There is also a collection of 300,000 modern eBooks that may be borrowed or downloaded by the print-disabled at OpenLibrary.org.
Both Archive.org and OpenLibrary.org provide APIs for accessing book metadata, fulltext, and more (where available) which you can learn about under this Books section.
The Internet Archive sees books as a fundamental mechanism for communicating knowledge and invests heavily in the digitization and accessibility of texts. Over 10M of these texts are publicly available, much in thanks to our partners, on archive.org and are accessible in various capacities through our metadata and book APIs.
There are still many texts the Internet Archive is not yet able to make publicly available. Where this is the case, the Internet Archive is still committed to helping the public learn where they might be able to find these works. As a result, the Internet Archive runs a project called the Open Library: an online public catalog of books the Internet Archive has available for reading or borrowing, as well as bibliographic records for 20+ millions of books which we don't.