CodePen - A front end web development playground.
myCompiler - Run your favourite programming languages online
JSFiddle - Test your JavaScript, CSS, HTML or CoffeeScript online with JSFiddle code editor.
CodeChef IDE - CodeChef IDE is a free online tool for developers helping them in writing codes and programs.
replit - Code, create, andlearn together. Use our free, collaborative, in-browser IDE to code in 50+ languages — without spending a second on setup.
Online Python - Online Python is a web application where you write codes in python language in the dedicated text space and the shell output is delivered to you in another text box on the right.