jQuery - The Write Less, Do More, JavaScript Library.
Documize - Enterprise-grade wiki and knowledge management platform
React - A JavaScript library for building user interfaces
HackMD - Fast and flexible, real-time collaborative markdown, inspired by Hackpad.
AngularJS - AngularJS lets you extend HTML vocabulary for your application. The resulting environment is extraordinarily expressive, readable, and quick to develop.
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.