Bun 1.4.0

OK BUN 1.4 JUST DROPPED. The all-in-one JavaScript toolkit just went nuclear. Period.

This is not a normal update. Bun literally rewrote itself from Zig to Rust — the entire runtime rebuilt. Period.

The Numbers Are Insane

Bun 1.4 adds +1,517 tests from the Node.js test suite — the biggest jump in Node compatibility since Bun 1.0 — and fixes over 2,900 issues. Period.

• 5x less idle CPU — your laptop fan can finally shut up.
• Up to 35% less memory — RAM stops being a luxury item.
• 50% faster startup on Linux — cold starts just got cold feet.
• 2,900+ issues fixed — the bug bash to end all bug bashes.

New APIs Everywhere

Bun.Image. Bun.WebView. Bun.markdown. Bun.cron(). Bun.Terminal. That is not a typo — it's a laundry list of brand-new toys. Period.

The CLI grew muscles too: bun run --parallel, bun test --parallel, plus bun audit fix, bun dedupe, and bun prune. Go clean out your node_modules rn.

The Ecosystem Just Works Now

Next.js 16 builds with Turbopack and the React Compiler. Vitest runs with coverage. Playwright drives real browsers. OpenTelemetry exports spans. dd-trace profiles continuously. Nuxt HMR, Fastify inject, TypeORM, nock — all working. Period.

This is the biggest Bun drop in a long, long time. Run bun upgrade and thank me later.