: While primarily known for classic literature, the collection includes audiobooks, maps, and specialized data sets.
: This key partner site facilitates the conversion of scanned physical books into e-books through a collaborative online process. Legal and Technical Framework Permission How-to - Project Gutenberg
: Although heavily English-centric (over 21,000 books as of 2008), it hosts significant collections in French, German, Finnish, Dutch, and dozens of other languages.
The library is built and maintained primarily by volunteers who digitize, proofread, and format the texts.