Box2D is an open source C++ engine for simulating rigid bodies in 2D. Box2D is developed by Erin Catto and has the zlib license. While the zlib license does not require acknowledgement, we encourage you to give credit to Box2D in your product.
Please file bugs or feature requests on the issues tab. Please only file bugs for the C++ version.
You can help support Box2D development with a donation.
You can read more detailed information about Box2D on their official FAQ.