Firefox Compiled into WebAssembly
Simon Willison · rss · 2026-07-17
Puter has successfully compiled Firefox into WebAssembly, achieving a "browser inside a browser" experience. The author demonstrated opening a Firefox instance within Chrome, even loading their own blog inside it.
Key Implementation Details
- Firefox / Gecko was chosen specifically for its better single-process support
- The project consumed approximately $25,000 worth of Claude Opus and Fable tokens
- Development was completed utilizing the Claude Max subscription plan
- All network traffic is forwarded to Puter's servers via WebSocket and the Wisp protocol
- This workaround is necessary because in-browser code cannot establish arbitrary network connections directly
Security and Networking
The author noted that the setup supports end-to-end encryption. By inspecting WebSocket messages, they confirmed that traffic to their own HTTPS site remained encrypted, whereas accessing http://www.example.com/ was transmitted in plaintext.
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