Rewriting Bun in Rust

TLDR · 1 week ago

Bun, a JavaScript runtime that processes 22 million monthly downloads, is being rewritten from Zig to Rust to systematically prevent memory safety bugs rather than fixing them one-by-one. The rewrite was completed in 11 days using Claude Code with approximately 50 dynamic workflows that mechanically ported 535,496 lines of Zig code while maintaining the existing test suite. This shift gives the Rust compiler the ability to catch use-after-free, double-free, and memory leak errors at compile time rather than relying on code review and runtime tools like address sanitizer.