Open Library provides RESTful API for accessing resources in multiple formats.
Earlier JSON API, which is deprecated now. This is retained only for backward compatibility and RESTful API should be used instead of this.
A Google dynlinks inspired API.
API to access book covers from Open Library.
If you want to a dump of complete data, please ask us by sending a mail to info@openlibrary.org. The APIs listed above should not be used for bulk download of Open Library data.
Are you using the Open Library APIs? Please let us know how your are using it by adding an entry in api_users page.