Solo dev builds full Rust browser engine from scratch with Claude Code — 91.4% WPT, 97.8% ECMAScript
PhallicPorsche · reddit · 2026-10-25
A solo developer spent months building a complete browser engine (Kingmaker / T.A.B.) in Rust from scratch with heavy Claude Code assistance — no Chromium, Electron, or WebView. It includes its own JS engine, bytecode VM, JIT compiler, DOM, CSS layout/painting, and WebAssembly runtime.
Conformance:
- WPT Testharness: 91.43%
- ECMAScript/Test262: 97.83%
- WebAssembly: 100%
- Combined: 92.22%, 1.76M+ passing tests across five suites
Design goals: low memory (hey.com at 246 MB in screenshots), small statically-linked dependency footprint, minimal Arc/Mutex/unsafe, and headless-first architecture meant for autonomous agents. Workflow: author owns architecture and direction; agents handle implementation, debugging, and testing, with the Rust compiler and upstream conformance suites as final judges. Real sites like Google and HEY already render; some pages still break.
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