CodePen - A front end web development playground.
Pastebin.com - Pastebin.com is a website where you can store text for a certain period of time.
JSFiddle - Test your JavaScript, CSS, HTML or CoffeeScript online with JSFiddle code editor.
Browxy - Browxy is a web application that serves as an integrated development environment where you can write in coding languages, compile them or edit them.
Liveweave - Liveweave is a HTML5, CSS3 & JavaScript playground for web designers and developers
CodeChef IDE - CodeChef IDE is a free online tool for developers helping them in writing codes and programs.