Firefox Compiled to WebAssembly: Simon Willison Runs His Own Blog in Firefox Running in Chrome

simonwillison.net·low signal

Willison highlighted a project compiling the entire Firefox browser to WebAssembly, demonstrating it by loading his own blog: 'Here's my blog, running in Firefox, running in WebAssembly, running in Chrome.' The practical significance is sandboxing — a full independent browser engine inside a Wasm boundary is a plausible substrate for running untrusted agent-driven browsing without host access. Given the week's Claude Code disclosures about sandbox boundaries and credential injection, browser-in-Wasm is a directly relevant isolation primitive.