Ustad Mobile is an open-source app that enables users to access a wide variety of open educational resources, online or offline. Both the app and content can be shared offline between devices.
Ustad Mobile features openly licensed content from some of the Internet's leading Open Educational Resources (OER) sites:
African Story Books
Global Digital Library
Khan Academy (including offline access to both videos and exercises)
Voice of America
Content is provided under license by external content providers. Ustad Mobile, unless explicitly mentioned otherwise, is not endorsed by any such content provider.