1) JS Fiddle
2) JS Bin
Cloud9 can do things in a very professional way and it is very helpful for beginners for quick learning. It supports different programming languages and environments like Ruby on Rails, WordPress, Node.js, Django etc. In the free version, resources are limited but you can use paid version for more resources.
Rendera is a free online coding application. Using Rendera you can save and export your work to your desktop or to any other place. It is built with Sinatra which is very lightweight and provides a good environment for beginners.
6) Application Craft
Application Craft provides 45 days free trial, and after that you have to pay for using it. It has rich features and puts significance on mobile development. It is also good at developing prototypes.
Nitrous is cloud-based coding platform. It is similar to Koding and provides a complete virtual machine with RAM and hard disk space for different programming languages. It also has a desktop application with collaboration facility.
SourceLair is a full cloud integration of Git and Mercurial. Everything is stored in the cloud and you can easily clone, commit, and pull. Django project is easily started in it. This IDE has integrated feature which allows deploying a new stack easily.
10) Live Weave
If you are interested in PHP Framework based web development, you should definitely check the list of Best 10 PHP Frameworks. Enjoy reading and stay updated.