CodeShare.io - Realtime code sharing for developers
HTML Code Play - Learn client side code like html, css, javascript,Angularjs, knockoutjs, bootstrap and more
Visual Studio Live Share - Real-time collaborative development
CodePen - A front end web development playground.
Teletype for Atom - Collaborate in real time in Atom
HTCSJS (HTmlCSsJS) - HTCSJS is an online HTML, CSS and JavaScript coding tool.