Blog | Bun

Fixes 271 issues, addressing 544 👍. bun fmt, a Prettier-compatible formatter built into Bun that is 3x to 6x faster than oxfmt, bun check is 1.4x to 7.8x faster on large projects, bun install migrates Yarn Berry lockfiles, retries with exponential backoff and closes 133 issues, up to 3.2x faster hoisted installs from a warm cache on Linux, bun pm fetch, bun publish --recursive, packageExtensions, Bun.SQL uses up to 48% less CPU per query, query.cancel(), COPY streams, column name transforms, user-defined functions and update hooks in bun:sqlite, ws rewritten to behave like npm ws on Node.js, ws.pause() and ws.resume() in Bun.serve, a JavaScriptCore upgrade with 54x faster toLocaleString, up to 2.8x faster Headers iteration, up to 2.6x faster response.body streams, extglob and brace ranges in Bun.Glob, a redesigned error overlay in the dev server, and many bugfixes and Node.js compatibility improvements.
Jarred · Jul 8, 2026
Jarred · Dec 2, 2025
Jarred, Lydia · Oct 28, 2025
Lydia · Sep 10, 2025
Fixes 166 issues, addressing 122 👍. bun check, a TypeScript type checker built into Bun that is 3x to 6.4x faster than tsc 7, --check for bun run, bun build and bun test, 67–89% less idle CPU, Bun.FetchSession, experimental Bun.ModuleGraph, --disallow-code-generation-from-strings, up to 2.7x faster large node:http responses, a JavaScriptCore upgrade with faster JSON.parse, faster rejected-promise handling, CompressionStream compression levels, If-Range support in Bun.serve, bun install skips tarballs it won't install, lower bun build memory with many entry points, [hashN] output names, profile-guided bytecode layout and faster startup for --compile --bytecode, and many bugfixes and Node.js compatibility improvements.
This release fixes two regressions impacting Elysia and AsyncLocalStorage, a hang in @discordjs/ws, CMYK JPEG decoding in Bun.Image, a rare JIT crash, and a GC crash on musl.
Fixes 202 issues, addressing 236 👍. HTTP/2 in Bun.serve, Bun.write() streams Response bodies to disk, self-contained workspace node_modules, bun install --offline and --prefer-offline, WebSocket pause() and resume(), crypto.argon2, tree-shaking through dynamic import(), smarter CommonJS to ESM conversion for default imports, --compile --bytecode when cross-compiling, smaller and faster-starting compiled executables, up to 9x faster Buffer reads and writes, 2x faster AsyncLocalStorage, faster startup, and many bugfixes and Node.js compatibility improvements.
Bun 1.4 rewrites Bun in Rust, ships built-in headless browser automation (Bun.WebView), Bun.Image, Bun.markdown, JSON5, JSONL, Terminal and cron APIs, Node.js 26.3.0 compatibility with 1,517 newly passing tests, parallel test and run, Windows ARM64, and an opt-in global virtual store for up to 7× faster installs.
Jarred, Ciro, Dylan, Alistair, Sosuke
Why & how we rewrote Bun from Zig to Rust
Fixes 92 issues (addressing 380 👍). Bun.Image — a built-in image processing API, 7x faster warm installs with the isolated linker's global store, experimental HTTP/2 and HTTP/3 clients for fetch(), HTTP/3 (QUIC) in Bun.serve(), rewritten fs.watch() on Linux and macOS, --no-orphans CLI flag, process.execve(), Bun.Terminal on Windows via ConPTY, FreeBSD and Android builds, shared SSL_CTX cache, smaller binaries, and many bugfixes and Node.js compatibility improvements.
Fixes 82 issues (addressing 381 👍). bun test --parallel, --isolate, --shard, and --changed, bun install streams tarballs to disk using 17x less memory, source maps use 8x less memory, 5.5x faster gzip with zlib-ng, Range request support in Bun.serve(), SHA3 in node:crypto and WebCrypto, ws+unix:// WebSocket client, and many bugfixes and Node.js compatibility improvements
Fixes 120 issues (addressing 219 👍). Render Markdown in the terminal with bun ./file.md, Bun.WebView headless browser automation, in-process Bun.cron() scheduler, async stack traces for native errors, 2.3x faster URLPattern, 2x faster Bun.Glob.scan, cgroup-aware parallelism on Linux, and many bugfixes and Node.js compatibility improvements.
Fixes 105 issues (addressing 307 👍). 4 MB smaller on Linux. x64 Bun.cron for OS-level cron jobs and expression parsing, Bun.sliceAnsi for ANSI/grapheme-aware string slicing, richer Bun.markdown list metadata; bun test --path-ignore-patterns; native Windows ARM64 .bin shim; dgram UDP fixed on macOS, fs.openSync numeric flags fixed on Windows (unbreaks tar@7), http2 WINDOW_UPDATE fix; bundler --bytecode/barrel/import-attribute fixes; CSS unicode-range/mask/border-radius fixes; Proxy-array crash fixes, CRLF injection fix, bun install hang fixes, and many Node.js compatibility improvements.
Fixes 155 issues (addressing 642 👍). New native REPL, --compile --target=browser for self-contained HTML, TC39 standard ES decorators, Windows ARM64 support, barrel import optimization, and a faster event loop. structuredClone up to 25x faster for arrays, Buffer.slice() 1.8x faster, path.parse() up to 7x faster, fewer closures in bundled output, and upgraded JavaScriptCore with 168x faster deep rope string slicing. Fixes Python asyncio-based MCP servers breaking with Bun.spawn(), plus numerous bugfixes across Node.js compatibility, bun install, the bundler, shell, and Windows.
Fixes 23 issues (addressing 13 👍). Run multiple scripts in --parallel or --sequential. bun:test mock & spyOn get Symbol.dispose support. ESM bytecode compilation. Faster Bun.markdown. Faster RegExp, String.prototype.trim, String.prototype.startsWith.
Fixes 8 issues (addressing 6 👍). Bun.markdown is a builtin CommonMark-compliant Markdown parser written in Zig. Bun's bundler gets bun build --metafile-md to write LLM-friendly module graph metadata. Fixes a regression in 'npm install -g bun' on Windows.
Fixes 91 issues (addressing 243 👍). 50% faster `Buffer.from(array)`, 35% faster async/await, 3x faster `array.flat()`, 90% faster `padStart`/`padEnd` via JSC upgrade. New: `Bun.JSON5`, `Bun.JSONL`, `Bun.wrapAnsi()` (33-88x faster than wrap-ansi npm), `--hea