CodePen is described as 'A communal platform for front-end development offering real-time previews, project building, and showcases, enhancing skills through challenges' and is a very popular Code Editor in the development category. There are more than 50 alternatives to CodePen, not only websites but also apps for a variety of platforms, including Self-Hosted, Linux, Mac and Windows apps. The best CodePen alternative is jsFiddle, which is free. Other great sites and apps similar to CodePen are Replit, Firebase Studio, Qoder IDE and CodeSandbox.