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I wanted to share a great online tool for anyone working with HTML, CSS, or JavaScript. CodePen.io is a free web based editor that makes it easy to experiment, prototype, and learn from other developers.
You can browse an extensive library of user created examples or create your own by starting a new “pen.” As you write your code, the preview updates instantly so you can see the results in real time. It is a simple, elegant, and highly effective way to test ideas or refine your skills.
If you work with front end code or enjoy experimenting with web design, give CodePen a try: http://codepen.io