OpenStax
OpenStax contains peer-reviewed textbooks. They are openly licensed and can be used online for free or printed at low cost. The books are created at Rice University with the help of grants from the Gates and Hewlett Foundations. Most of the books have free resources for faculty (available only after verification of faculty affiliation) and resources for students. OpenStax also partners with for-profit education companies to provide additional (paid) resources. The platform is focusing primarily on basic and introductory courses, but is growing rapidly. Textbooks include titles on Principles of Economics, Principles of Microeconomics and Principles of Macroeconomics.