Published by librarians at McMaster University, the OER By Discipline Guide lists relevant open textbooks for subject areas ranging from the liberal arts and social sciences to engineering.
An open textbook project developed at Rice University, OpenStax offers open introductory textbooks that can be accessed in different formats. Books are also available in print, for a fee. All OpenStax texts have a CC-BY license, which allows users to remix and redistribute the work, so long as the original work is credited.
The LibreText Commons hosts curated Open Educational Resources from all 16 libraries in the LibreVerse in one convenient location. We believe everyone should have access to knowledge and we are happy to share our OER corpus to everyone completely free.
LibreTexts is the adaptable, user-friendly non-profit open education resource platform that educators trust for creating, customizing, and sharing accessible, interactive textbooks, adaptive homework, and ancillary materials. We collaborate with individuals and organizations to champion open education initiatives, support institutional publishing programs, drive curriculum development projects, and more.
The Open Textbook Library at the University of Minnesota hosts nearly 700 open textbooks in a range of disciplines, which can be downloaded in multiple formats. Pay attention to the Creative Commons license of any book you may want to use, as remixes may not be a permitted use.
Open Textbooks at OER Commons offers curated collections of textbooks by subject as well as links to Higher Education Open Providers. The collection offers links to repositories sponsored by different institutions, such as: BC Campus, CUNY Academic Works, OpenOregon, and more.