College Open Textbooks (COT) focuses on textbooks for lower division classes. COT is not a repository in itself; their listings point to textbooks in other repositories.
These books have been reviewed by faculty from a variety of colleges and universities to assess their quality. These books can be downloaded for no cost, or printed at low cost. All textbooks are either used at multiple higher education institutions; or affiliated with an institution, scholarly society, or professional organization.
The Directory of Open Access Books is another initiative of the Open Access Publishing in European Networks. They refer to this as a "discovery service" for open access books.
The Open Access Publishing in European Networks (OAPEN) Foundation is a not-for-profit organisation based in the Netherlands, dedicated to creating and disseminating open access, peer-reviewed books.
InTech publishes more than 2,300 open textbooks and 6 journals in a variety of subjects.
Lumen Learning offers open courses in a variety of high-demand subjects and disciplines. These courses are collections of high-quality OER, not necessarily as a traditional textbook. You can use them as-is or modify them to fit your instructional style and students’ needs.
MIT OpenCourseWare (OCW) is a web-based publication of virtually all MIT course content. OCW is open and available to the world and is a permanent MIT activity.
Multiple Types of Resources
MERLOT is a curated collection of free and open online teaching, learning, and faculty development services contributed and used by an international education community. The MERLOT Collection is made up of over 40,000 materials in 19 different material type categories.
Open Learn is an initiative of The Open University, UK. It provides supplemental materials for educators, including articles, podcasts, videos, games, and much more. In addition, it offers more than 700 free online classes.
OER Commons helps educators, students, and lifelong learners avoid time-consuming searches and find exactly the right materials. With a single point of access from which they can search, browse, and evaluate resources in OER Commons’ growing collection of over 50,000 high-quality OER everyone can more efficiently find what they need.
Searches 15 OER repositories simultaneously.