Example code to give you an idea of the API:

ammo.js is a direct port of the Bullet physics engine to JavaScript, using Emscripten. The source code is translated directly to JavaScript, without human rewriting, so functionality should be identical to the original Bullet.

Note: ammo.js has just been updated to a new porting approach. If you find some part of the Bullet API that is not supported that you need, please see

‘ammo’ stands for “Avoided Making My Own js physics engine by compiling bullet from C++” ;)

ammo.js is zlib licensed, just like Bullet.

Discussion takes place on IRC at #emscripten on Mozilla’s server (


builds/ammo.js contains a prebuilt version of ammo.js. This is probably what you want.

You can also build ammo.js yourself, as follows:


The most straightforward thing is if you want to write your code in C++, and run that on the web. If so, then compile your code into LLVM, link it with bullet, and compile that to JavaScript using emscripten. (The easiest way to link it is to add your .bc file to the llvm-link command in

If, on the other hand, you want to write code in JavaScript, you can use the autogenerated binding code. A complete example appears in


That is HelloWorld.cpp from Bullet, translated to JavaScript. Other examples in that directory might be useful as well. In particular see the WebGL demo code in


Bindings API

ammo.js autogenerates its API from the Bullet source code, so it should be basically identical. There are however some differences and things to be aware of:


Reporting Issues

If you find a bug in ammo.js and file an issue, please include a script that reproduces the problem. That way it is easier to debug, and we can then include that script in our automatic tests.

Release Process

Pushing a new build in builds/ammo.js should be done only after the following steps:

Upstream Version

Bullet 2.82

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