What programming language does CodePen use?

Alex does JavaScript development for CodePen, both front end and back, as well as Rails and just about everything else. @alexquez on Twitter and @quezo on CodePen.

Pros: CodePen is an excellent web-based IDE for web and front-end development . The site supports HTML, CSS, JavaScript and more. One of the best features is the challenges. Every month the community completes themed challenges to hone the skills.