Write HTML, CSS and JavaScript in the browser and share it as a live demo.
CodePen is an online editor where you write HTML, CSS and JavaScript and see the result live. Each "Pen" can be forked, embedded in articles and collected into Collections.
It supports CSS and HTML preprocessors and adding JavaScript libraries. Many CSS demos and bug reports are shared as Pens.
The free plan covers public Pens. Paid PRO plans add private Pens, asset hosting, Collab Mode and Professor Mode.