Open Library - thoth-pub/thoth GitHub Wiki
Open Library is a digital library project by the Internet Archive, providing access to a large variet of books through its Open Library Explorer portal.
The portal provides an openly-available RESTful API, best used to link into Open Library data in JSON, YAML and RDF/XML. Open Library also encourages the use of established bibliographic standards including MARC21, UniMARC & ONIX. Catalog record dumps are available in JSON format.