Library Genesis, commonly called LibGen, is one of the largest shadow libraries on the internet. It hosts millions of books and academic articles, including textbooks, monographs, and journal papers that would otherwise require purchase or a library subscription. The collection spans multiple languages and disciplines, with search by title, author, ISBN, or DOI. Files are available in PDF, EPUB, and other formats.

Like Sci-Hub, LibGen operates outside copyright law in most countries and has been the subject of legal action by publishers. It's used heavily by students and researchers who lack access to well-funded libraries. The site describes itself as a "links aggregator" rather than a host, though functionally it serves the same purpose. As with any shadow library, users should consider the legal and ethical implications in their own context.