fastpen is described as 'Fastpen is an open source alternative to codepen that just stores the source code compressed, in the url' and is a Code Editor in the development category. There are more than 25 alternatives to fastpen, not only websites but also apps for a variety of platforms, including Self-Hosted, Android, Mac and Windows apps. The best fastpen alternative is Replit, which is free. Other great sites and apps similar to fastpen are CodePen, jsFiddle, JSPad and JS Bin.
Codeply is a editor that lets you run and preview your HTML, CSS and JavaScript code from any modern Web-browser. You've seen this capability in other tools like JSFiddle, Codepen and Bootply. But, Codeply is different because it's not just a code editor.
