Firepad : Firepad is an open-source, collaborative code and text editor. It is designed to be embedded inside larger web applications.
Teletype for Atom : Teletype for Atom lets developers share their workspace with team members and collaborate on code in real time.
Closure Tools : The Closure Compiler, Library, Templates, and Stylesheets help developers create powerful and efficient JavaScript.
EtherPad : Etherpad is an Open Source online editor providing collaborative editing in really real-time powered by Node.js
MobWrite converts forms and web applications into collaborative environments. Create a simple single-user system, add one line of JavaScript, and instantly get a collaborative system.