CodePen – Front End Developer Playground & Code Editor in the Browser

We call them Pens. Write HTML, CSS, and JS and get a real-time preview. You can use CodePen to:

  • Show off the amazing things you build.
  • Learn new things by tinkering.
  • Build reduced test cases to report bugs and get help on tricky problems.
  • Try out new technologies for the first time.
  • Build components to later use elsewhere.

The possibilities are endless. Everything you do is saved on CodePen, so the more you use it the more useful it become

A front end web development playground.

Source: CodePen – Front End Developer Playground & Code Editor in the Browser