Welcome!

SpiderMonkey is Mozilla’s JavaScript and WebAssembly Engine, used in Firefox, Servo and various other projects. It is written in C++, Rust and JavaScript. You can embed it into C++ and Rust projects, and it can be run as a stand-alone shell.

What's New


Read more in the SpiderMonkey Blog

SpiderMonkey Internals


Understanding the engine

In-depth Articles:

Building and Contributing


Embedding SpiderMonkey


Where to find us