February 23, 2026
Rusty bird, spicier comments
Ladybird Browser adopts Rust
From C++ to Rust: applause, side‑eyes, and “did AI write this”
TLDR: Ladybird is starting to replace parts of its browser engine with Rust, using AI-assisted translation that keeps results identical and performance steady. The community is split: some celebrate safety and pragmatism, while others question C++ interop, the AI role, and whether this slows the project.
Ladybird, the indie web browser, just declared it’s moving chunks of its engine from old-school C++ to Rust—a language loved for safety and speed. Founder Andreas Kling says the first big piece, the JavaScript engine, was ported with help from AI assistants and now produces identical results with no performance loss. But the community? Absolutely lit.
The loudest skeptics snapped, “But Rust doesn’t have C++ interop at all?”—calling out the pain of mixing two worlds. Others blasted the headline for dodging the AI angle, accusing it of PR gloss. Cynics joked the launch date just evaporated: “See you in 2029.” Meanwhile optimists cheered, saying this proves coding agents can help build entire operating systems.
Fans loved the “byte-for-byte identical” flex, but the phrase “not idiomatic Rust… cleanup will come” sparked drama. One commenter asked if “cleanup” means a full do-over later—translation: more work, more delays. Memes flew: “Rusty Bird,” “lockstep mode = training wheels,” and “bytecode or bust.”
Context for non-nerds: Rust aims to prevent memory bugs that crash apps; C++ is fast but risky. Ladybird will run both languages side-by-side for now, with careful boundaries. The real show is in the comments: a mix of claps, groans, and AI side-eye that turns this tech shift into a soap opera.
Key Points
- •Ladybird is migrating parts of its C++ codebase to Rust, starting with the LibJS JavaScript engine.
- •The team previously rejected Rust over OOP fit but now cites Rust’s ecosystem, safety, and contributor familiarity; Swift was declined due to C++ interop and platform support limits.
- •LibJS lexer, parser, AST, and bytecode generator were ported using human-directed AI tools (Claude Code, Codex) with adversarial reviews.
- •The Rust port totals ~25,000 lines completed in about two weeks, achieving byte-for-byte identical AST and bytecode outputs and zero performance regressions.
- •C++ remains the main development focus; Rust ports will proceed gradually with interop boundaries, managed by the core team, with later cleanup toward idiomatic Rust.