Doxygen - Generate documentation from source code
Penflip - Typewrite is a real-time collaborative writing environment with Markdown support, versioning and Dropbox syncing. Alternatives to Penflip for Web, Windows, Mac, Linux, iPhone and more.
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
Cleartext - A text editor that allows only the 1,000 most common words
Docsify.js - A magical documentation site generator.
Quill - Powerful, API-driven rich text editor