This is a JavaScript Version of Box2D 2.1a Open examples/index.html to see it in action or watch it online at http://heikobehrens.net/box2d.js Also, box2d.js became part of cocos2d-javascript. Have a look at it's demo page http://cocos2d-javascript.org/demo?demo=box2d Box2D (original C++ version) http://www.box2d.org Box2DFlash (maintained port to AS3) http://www.box2dflash.org Box2DJS (outdated port to JS) http://box2d-js.sourceforge.net Thanks to Jonas Wagner for getting things rolling http://29a.ch/2010/4/17/box2d-2-flash-ported-javascript (I will write more about this project, soon)