CodePen!

Pastebin.com is a website where you can store text for a certain period of time. The website is mainly used by programmers to store pieces of sources code or configuration information, but anyone is more than welcome to paste any type of text. The idea behind the site is to make it more convenient for people to share large amounts of text online. Users have the ability to make private pastings, so they are only visible to the people they choose to share their links with.

jsFiddle lets one easily test snippets of JavaScript/CSS/HTML code on-the-fly, adding optional libraries like jQuery.

JS Bin is a collaborative open source JavaScript debugging tool. Enter Javascript in one pane and HTML in the other and see the result; share using a short URL. Choose popular JS libs from a menu, so you don't have to remember the URL.

Online Interpreters in JavaScript. Online coding and REPL. Run and share code. Try QBasic, Forth, Ruby, Python, Lua, Scheme, Emoticon, Brainfuck, LOLCODE, Unlambda, Bloop, JavaScript, Javascript.next, Move, Kaffeine, CoffeeScript, Roy programming languages.

Plunker is an online community for creating, collaborating on and sharing your web development ideas.

kodeWeave is a realtime coding playground for HTML, CSS and Javascript. Similar to JSFiddle and JSBin, but kodeWeave was made to work offline but also as a prototyping application to build applications for desktop operating systems while on mobile devices. (PhoneGap Build is recommended for mobile devices)

dabblet is an interactive playground for quickly testing snippets of CSS and HTML code. It uses -prefix-free, so that you won't have to add any prefixes in your CSS code. You can save your work in Github gists, embed it in other websites and share it with others.

Compile and Execute your favorite programming languages online, click any of the following to proceed! Web Technologies, Text Formatting, Useful Utilities, Programming Languages. Vim, emacs modes are avaliable.

Publish HTML quickly with open source web editor, HTMLhouse. Use the editor / real-time preview to build your HTML page, and press publish when you're done. That's it! No sign up, no fuss.

Its about quite a few things. You can use CSSDeck to make testcases and share with other people on IRC, forums, StackOverflow, etc. who help you solve your coding problems. You can even code with multiple people in realtime in various modes. Remember etherpad ? Yeah we've got something like that for HTML/CSS/JS coding with lots of other bells and whistles.

Is your code your art? Be awarded a commission alongside some of the world's best interactive artists at the Barbican, London.

Web Maker is an easy, quick and offline web experiment playground available as a Chrome extension, with open source code available at GitHub.

Instantly write and execute code collaboratively with a candidate, right in the browser. CodeBunny provides a Realtime Collaborative Editorwith in-browser Code Execution and REPL (read-eval-print-loop) shells. CodeBunny is an Online Compiler and Interpreter for PHP, Python, Ruby, Perl, Javascript, C, C++, Java, Clojure, R, Scala, Coffeescript. Ideal for Phone Screen/Online Interview of Developers. CodeBunny also enabled video chatting with Google Hangouts.

Feditor.IO is an instant code editor for front-end developers and designers:* It is simple to use, so simple - no tons of useless features or extra large buttons which shrink your workspace* It has a built-in console - no need to open external dev-tools while working on your JavaScript file* It supports live reload - see the preview & console content changes as you type* It saves changes automatically - your code and even your customized layout will be here even after a shutdown...and many more! »

CodeBunk provides a Realtime Collaborative Editor with Compile/Run. CodeBunk is an Online Compiler/Interpreter for PHP, Python, Ruby, Perl, Lua, Javascript, C, C++. CodeBunk also has Peer-to-Peer Video/Audio chat facility. CodeBunk is ideal for Online Interview of Developers as well as Learning to code from Friends.