Firefox in WebAssembly
Simon Willison Simon Willison
Puter compiled Firefox to WebAssembly, enabling the browser to run inside another browser like Chrome. The project cost approximately $25,000 in Claude Opus and Fable API tokens and routes all traffic through WebSockets via Puter's servers to work around browser network restrictions. This allows Firefox to function as a fully nested application while maintaining end-to-end encryption for HTTPS traffic.
Why it matters
Firefox in WebAssembly This is absurdly cool: Puter compiled Firefox to WebAssembly such that the whole browser runs in another browser. Here's my blog, running in Firefox, running in WebAssembly, running in Chrome: They chose Firefox/Gecko because it has strong single-process support. The project took an estimated $25,000 of Claude Opus and Fable tokens, taking advantage of a Claude Max subscription plan. The demo funnels all traffic over a WebSocket protocol (using the Wisp protocol) through Puter's server - a requirement to get this kind of thing to work because code running in browsers can't open arbitrary network connections. (That proxying sounds expensive! The team had to scale the servers up to handle the traffic during the Hacker News conversation about the project.) Puter claim this supports end-to-end encryption and that looks to be true - I inspected the WebSocket messages and traffic to my own HTTPS site was encrypted whereas requests and responses to http://www.example.co
