Box2dhx2.1a is a project mainly written in Haxe, it's free.
A port from box2d flash 2.1a to haxe
Box2D 2.1a finally ported!!! :D...
But there is some known bugs... The Continous Collision Detection is bugging. So be sure to turn off the CCD feature with world.SetContinuousPhysics(false);
If you want to send a patch for fixes, contact me in alijayameilio[at]gmail[dot]com or just hit the issues. I will be glad if you help me :D
For complete information about Box2D 2.1a you can see in http://www.box2dflash.org/
There are differences between the flash version and haXe version... this is the list:
For note... this library hasn't been optimized, so the next thing must do is: