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[ARTICLE · art-62903] src=simonwillison.net ↗ pub= topic=artificial-intelligence verified=true sentiment=· neutral

Firefox in WebAssembly

Puter released a demo of Firefox running in WebAssembly inside a Chrome browser, using an estimated $25,000 in Claude Opus and Fable tokens under a Claude Max subscription plan. The project compiles the Gecko engine to WASM and routes all traffic through Puter's server via the Wisp WebSocket protocol, with the team scaling servers to handle Hacker News traffic. Puter claims end-to-end encryption, verified by inspecting WebSocket messages.

read1 min views52 publishedJul 16, 2026

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.com/

were in cleartext.

Here's the repo for firefox-wasm . theogbob/WebkitWasm is a similar project that compiles WebKit to WASM, but that one doesn't currently have an accessible online demo.

Via [Hacker News](https://news.ycombinator.com/item?id=48926939)

Tags: [browsers](https://simonwillison.net/tags/browsers), [firefox](https://simonwillison.net/tags/firefox), [ai](https://simonwillison.net/tags/ai), [webassembly](https://simonwillison.net/tags/webassembly), [generative-ai](https://simonwillison.net/tags/generative-ai), [llms](https://simonwillison.net/tags/llms), [ai-assisted-programming](https://simonwillison.net/tags/ai-assisted-programming), [claude](https://simonwillison.net/tags/claude), [claude-mythos-fable](https://simonwillison.net/tags/claude-mythos-fable)
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