JS Bin was built by Remy Sharp and is completely open source and available http://github.com/remy/jsbin. You can also follow @rem on Twitter where he'll tweet about JavaScript, HTML 5 and other such gems.

JS Bin is a webapp specifically designed to help JavaScript and CSS folk test snippets of code, within some context, and debug the code collaboratively.

JS Bin allows you to edit and test JavaScript and HTML (reloading the URL also maintains the state of your code - new tabs doesn't). Once you're happy you can save, and send the URL to a peer for review or help. They can then make further changes saving anew if required.

If you want a lightweight debugger tool that you can write your code from every where then you should use it now , and it’s really have a friendly UI .