Firefox in WebAssembly
A developer named Puter has accomplished a remarkable technical feat: compiling the Firefox browser to WebAssembly so that the entire browser runs inside another browser. The project demonstrates just how far WebAssembly has come as a platform for running complex native applications.
Simon Willison documented the achievement on his blog, showing a screenshot of his own site running inside Firefox, which was running inside WebAssembly, which was running inside Chrome. The stack illustrates the layered nature of the implementation.
Why Firefox and How It Works
The team chose Firefox and its Gecko rendering engine because of its strong single-process support. This made it easier to compile the browser to WebAssembly without the complications that come with multi-process architectures.
The project required significant computational resources. Puter estimated that the effort consumed approximately $25,000 worth of Claude Opus and Fable tokens, taking advantage of a Claude Max subscription plan to keep costs manageable.
Network Proxy Requirement
This proxying arrangement proved expensive to operate. The team had to scale up their servers to handle the traffic surge that came when the project was discussed on Hacker News.
Stay ahead of the AI curve
The most important updates, news, and content — delivered weekly.
No spam. Unsubscribe anytime.
Security and Encryption
Puter claims that the setup supports end-to-end encryption. Willison verified this claim by inspecting the WebSocket messages. Traffic to his own HTTPS site was encrypted, while requests and responses to http://www.example.com/ appeared in cleartext. This confirms that the encryption is working as expected.
Related Projects
The code for the Firefox-in-WebAssembly project is available in the firefox-wasm repository. A similar project called WebkitWasm, by developer theogbob, compiles WebKit to WASM. However, that project does not currently have an accessible online demo.
Background
WebAssembly, or WASM, is a binary instruction format that allows code written in languages like C, C++, and Rust to run in web browsers at near-native speed. Compiling an entire browser like Firefox into WASM is a significant achievement that pushes the boundaries of what the technology can do.
Puter is known for building a browser-based operating system that runs in the cloud. The company has been exploring ways to bring desktop-class applications to the web.
Related on Neura Market
- AI Tools Directory, Explore tools like Claude Opus and Fable used in this project.
- Developer Tools Marketplace, Find resources for WebAssembly and browser development.
- WebAssembly Platform Directory, Learn more about WASM projects and implementations.