Andrej Karpathy boosts Bun's rewrite from JavaScript to Rust
As seen on the 24/7 Wall St. homepage on July 9, 2026.
Karpathy's amplification signals major infrastructure momentum as Bun ditches JavaScript for Rust, reshaping the web runtime race.
RT @jarredsumner: Rewriting Bun in Rust https://t.co/Rl8bcaxBFc
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Jarred Sumner, the creator of Bun, announced that the runtime is being rewritten in Rust, a move away from the JavaScript and Zig foundations that defined its earlier architecture. Karpathy's decision to retweet the announcement to his large audience is a notable signal of attention from the AI and engineering community, which watches infrastructure shifts closely.
Bun has positioned itself as a fast, all-in-one JavaScript runtime and toolkit designed to compete with Node.js and Deno. A shift to Rust, a language prized for memory safety and performance, would represent a significant architectural bet — one that has drawn 865 retweets as of July 9, 2026, suggesting the news is spreading quickly through technical circles.
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What to watch is how the Bun team communicates the scope and timeline of the rewrite, and whether the move accelerates or temporarily disrupts the runtime's development cadence. Karpathy's amplification brings the story to audiences well beyond the JavaScript ecosystem.