Why Bun Was Rewritten from Zig to Rust
Content is AI-assisted and may contain inaccuracies.
Bun creator Jarred Sumner has published a detailed article explaining the decision to rewrite Bun's core from Zig to Rust. Rather than criticizing Zig, the post focuses on the engineering challenges of maintaining a large JavaScript runtime that combines garbage-collected and manually managed memory. The rewrite aims to improve memory safety, stability, and long-term development velocity while preserving Bun's architecture and behavior. The article also offers an in-depth look at the engineering process behind the migration, including AI-assisted development workflows, automated testing, and large-scale code review that made the rewrite possible.