An open textbook is a textbook licensed under an open copyright license, and made available online to be freely used by students, teachers and members of the public. Many open textbooks are distributed in either print, e-book, or audio formats that may be downloaded or purchased at little or no cost. (Wikipedia)
- Bartleby – the preeminent Internet publisher of literature reference and verse providing students, researchers and the intellectually curious with unlimited access to books and information on the web, free of charge.
- Boundless – has 21 college level subjects textbook
- CK-12 Flexbooks – contains of K-12 open textbooks and variety kind of learning objects, also includes teaching resources.
- College Open Textbooks – lists open textbooks by subject, many of which have been peer reviewed.
- Connexions – more than tens of thousands of learning objects called pages, that are organized into thousands of textbook-style books in a host of disciplines, all easily accessible online and downloadable to almost any device, anywhere, anytime.
- Flat World Knowledge – is the largest publisher of open college textbooks for students worldwide.
- Open Library – one web page for every book. Open Library is an open project: the software is open, the data are open, the documentation is open which had gathered over 20 million records to date.
- Open Textbook Library – hosted by the University of Minnesota, this site contains open textbooks covering Business, Management and Marketing, Accounting and Finance, Computer Science and Information System, Economics, General Education, Humanities and Languages, Law, Mathematics and Statistics, Natural and Physical, Social Sciences.
- Open Textbook Project – a collection of 40 existing open textbooks curated by BCcampus and available for reuse and adaptation.
- OpenStax CNX Library – offers modules (small knowledge chunks) or collections (structured into books or course notes) covering Art, Business, Humanities, Mathematics and Statistics, Science and Technology and Social Sciences.
- Orange Grove Text – program works with Florida Virtual Campus and the University Press of Florida to curate and publish open textbooks.
- Textbook Revolution – is a student-run site dedicated to increasing the use of free educational materials by teachers and professors. We want to get these materials into classrooms. On this site you'll find links and reviews of textbooks and select educational resources. Some of the books are PDF files, others are viewable online as e-books, or some are simply web sites containing course or multimedia content.
- The Saylor Foundation – a free and open collection of college-level courses.
- E-Books on the Web – University at Buffalo Libraries website provide a single search from multiple sources for open textbook.
- Free Book Centre – contains links to thousands of free online technical books. Which Include core computer science, networking, programming languages, Systems Programming books, Linux books and many more.
- Librivox – Free public domain audiobooks.
- Project Gutenberg – offers over 45,000 free ebooks: choose among free epub books, free kindle books, download them or read them online.
- The Internet Archive – A non-profit, is building a digital library of Internet sites and other cultural artifacts in digital form. Like a paper library, we provide free access to researchers, historians, scholars, the print disabled, and the general public.