Google Books is the public facing side of a major initiative by Google to preserve digital copies of print books. Since the goal is to digitize all books and not just those out of copy right not all books in the collection are availabe to the public. Some are out of copyright or licensed to be viewed in their entirety, some are licensed to have previews shown, some are licensed to just show snippets of the book where search terms appear in context, and some are not licensed to be publicly available and will just show a book record in the place of the actual book.

Through the work of volunteers, Project Gutenberg has digitized almost 60,000 free ebooks. Most books in the collection are no longer in copyright, however some still are so you should always check the included license info.

A project of OAPEN based in the National Library at The Hague, DOAB is an online directory for academic books published under open access licenses. Publishers must fill out an application form and meet specific parameters of academic scholarship and peer review for their books to be included in the resource.

Volunteers for LibriVox have taken works in the public domain and read them aloud to record audio versions of the book. All works in LibriVox's library are in the public domain so newer titles will not be available here.