Developed at SUNY Geneseo's Milne Library, Openly Available Sources Integrated Search (OASIS) is a search tool that aims to make the discovery of open content easier. OASIS currently searches open content from 71 different sources.

The MERLOT collection consists of tens of thousands of discipline-specific learning materials and exercises, created by an international community of educators, learners, and researchers. All the materials in MERLOT are reviewed for suitability for retention in the collection, and many undergo the extensive peer review for which MERLOT is famous.

OpenStax is a nonprofit educational initiative based at Rice University. They publish high-quality, peer-reviewed, openly licensed college textbooks that are free online and low cost in print. OpenStax textbooks are being used in 48% of college and universities in the U.S. and in over 100 countries.

Hosted by the University of Minnesota and supported by the Open Textbook Network, the Open Textbook Library is a collection of textbooks that have been funded, published, and licensed to be freely used, adapted, and distributed. These books have been reviewed by faculty from a variety of colleges and universities to assess their quality and can be downloaded for no cost, or printed at low cost.

OER Commons is a public digital library of open educational resources. Provides a fully searchable catalog including hundreds of open textbooks for use in higher education.

BCcampus provides a collection of open textbooks aligned with the highest-enrolled subject areas, as well as a selection of books for trades, technology, and skills training. Books can be browsed by subject area, and many are faculty reviewed.

The American Institute of Mathematics (AIM) seeks to encourage the adoption of open source and open access mathematics textbooks. The AIM Editorial Board has developed evaluation criteria to identify the books that are suitable for use in traditional university courses and maintains a list of approved textbooks which have been judged to meet these criteria.

The Center for Open Educational Resources & Language Learning (COERLL) produces resources to help improve the teaching and learning of over 20 foreign languages.