ATutor - Free, open source LMS with integrated social networking
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
Sublime Tutor - Learn Sublime Text from a tutor who sits inside the editor
MkDocs - Project documentation with Markdown.
TutorMe - Connect with a high-quality tutor in under 30 seconds
Docusaurus - Easy to maintain open source documentation websites