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. It can also be compiled to WASI; see our online demo.
What's New
Read more in the SpiderMonkey Blog
SpiderMonkey Internals
Understanding the engine
In-depth Articles:
- Warp: Improved JS Performance
- Compiler Compiler: A Twitch series
- A New RegExp Engine
- Future-proofing the Debugger Implementation
- The Baseline Interpreter
Building and Contributing
Embedding SpiderMonkey
- Examples and Documentation
- mozilla.dev.tech.js-engine (ARCHIVED)
- mozilla.dev.tech.js-engine.internals (ARCHIVED)
Where to find us
- Matrix chat: #spidermonkey:mozilla.org
- Discourse: SpiderMonkey
- Mastodon: SpiderMonkey@mozilla.social
While we strongly recommend using Matrix chat if you have questions, we also maintain a non-exhaustive list of people who have volunteered their expertise on specific components of SpiderMonkey. For example, you might need to know who to needinfo about IonMonkey in Bugzilla…