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d="M9 3h8l4 4v10H9z"/><path d="M6 6.5V20h11"/><path d="M3 8v13h11"/></svg></span>Bundler</a><a class="inline-flex h-11 shrink-0 items-center gap-1.5 whitespace-nowrap border-b-2 px-2.5 text-[14px] font-medium transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/test" data-link="" data-prefetch="hover"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 opacity-80"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M8.5 3h7"/><path d="M10 3v5L4 20h16L14 8V3"/><path d="M7 14h10l3 6H4z" fill="currentColor" opacity="0.3" stroke="none"/><path d="M7.5 14h9"/></svg></span>Test Runner</a><a class="inline-flex h-11 shrink-0 items-center gap-1.5 whitespace-nowrap border-b-2 px-2.5 text-[14px] font-medium transition-colors border-transparent text-fg-muted 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fill="currentColor" opacity="0.3" stroke="none"/><path d="M10.5 7H17v3.5h-6.5z"/><path d="M10.5 14H18M10.5 17H15"/></svg></span>Blog</a><a class="inline-flex h-11 shrink-0 items-center gap-1.5 whitespace-nowrap border-b-2 px-2.5 text-[14px] font-medium transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/feedback" data-link="" data-prefetch="hover"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 opacity-80"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M8.5 3h7L19 6.5v5L15.5 15v3h-7v-3L5 11.5v-5z"/><path d="M10 9.5l2 2 2-2M12 11.5V18"/><path d="M9.5 21h5"/></svg></span>Feedback</a></div></nav><div class="mx-auto flex w-full max-w-[100rem]"><button type="button" aria-expanded="false" aria-controls="docs-sidebar-rail" class="mono fixed 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class="inline-flex h-9 w-9 items-center justify-center rounded-full border border-line"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter" aria-hidden="true" class="h-4 w-4"><path d="M6 6l12 12"></path><path d="M18 6L6 18"></path></svg></button></div><nav id="docs-sidebar" aria-label="Runtime navigation" class="px-5 py-6 md:pl-gutter md:pr-4"><ul class="flex flex-col gap-7"><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M3 4h14l4 4v12H3z"/><path d="M7 10l3 3-3 3"/><path d="M12.5 16H17"/></svg></span>Get Started</p><ul class="border-l border-line"><li><a aria-current="page" 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1Core Runtime</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime" data-link="" data-prefetch="hover">Bun Runtime</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/watch-mode" data-link="" data-prefetch="hover">Watch Mode</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/debugger" data-link="" data-prefetch="hover">Debugging</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/repl" data-link="" data-prefetch="hover">REPL</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/bunfig" data-link="" data-prefetch="hover">bunfig.toml</a></li></ul></li><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M5 3h9l5 5v13H5z"/><path d="M14 3v5h5"/></svg></span>File & Module System</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/file-types" data-link="" data-prefetch="hover">File Types</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/module-resolution" data-link="" data-prefetch="hover">Module Resolution</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/jsx" data-link="" data-prefetch="hover">JSX</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/auto-install" data-link="" data-prefetch="hover">Auto-install</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/plugins" data-link="" data-prefetch="hover">Plugins</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/file-system-router" data-link="" data-prefetch="hover">File System Router</a></li></ul></li><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M3 3h15l3 3v4H3z"/><rect x="3" y="14" width="18" height="7"/><rect x="6" y="5.5" width="2" height="2" fill="currentColor" stroke="none"/><rect x="6" y="16.5" width="2" height="2" fill="currentColor" stroke="none"/><path d="M13 6.5h4M13 17.5h4"/></svg></span>HTTP server</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/http/server" data-link="" data-prefetch="hover">Server</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/http/routing" data-link="" data-prefetch="hover">Routing</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/http/cookies" data-link="" data-prefetch="hover">Cookies</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/http/tls" data-link="" data-prefetch="hover">TLS</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/http/error-handling" data-link="" data-prefetch="hover">Error Handling</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/http/metrics" data-link="" data-prefetch="hover">Metrics</a></li></ul></li><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M8 3h8l5 5v8l-5 5H8l-5-5V8z"/><path d="M3 12h18"/><path d="M10 3.5L8 8v8l2 4.5M14 3.5l2 4.5v8l-2 4.5"/></svg></span>Networking</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/networking/fetch" data-link="" data-prefetch="hover">Fetch</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/http/websockets" data-link="" data-prefetch="hover">WebSockets</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/networking/tcp" data-link="" data-prefetch="hover">TCP</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/networking/udp" data-link="" data-prefetch="hover">UDP</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/networking/dns" data-link="" data-prefetch="hover">DNS</a></li></ul></li><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M4 5.5l2-2h12l2 2-2 2H6z" fill="currentColor" opacity="0.3" stroke="none"/><path d="M6 3.5h12l2 2v13l-2 2H6l-2-2v-13z"/><path d="M4.5 6L6 7.5h12L19.5 6"/><path d="M4.5 12.5L6 14h12l1.5-1.5"/></svg></span>Data & Storage</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/cookies" data-link="" data-prefetch="hover">Cookies</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/file-io" data-link="" data-prefetch="hover">File I/O</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/streams" data-link="" data-prefetch="hover">
1Streams</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/binary-data" data-link="" data-prefetch="hover">Binary Data</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/archive" data-link="" data-prefetch="hover">Archive</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/sql" data-link="" data-prefetch="hover">SQL</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/sqlite" data-link="" data-prefetch="hover">SQLite</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/s3" data-link="" data-prefetch="hover">S3</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/redis" data-link="" data-prefetch="hover">Redis</a></li></ul></li><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M12 21v-9L4.5 4.5"/><path d="M12 12l7.5-7.5"/><path d="M4 10V4h6"/><path d="M20 10V4h-6"/></svg></span>Concurrency</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/workers" data-link="" data-prefetch="hover">Workers</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/module-graph" data-link="" data-prefetch="hover">ModuleGraph</a></li></ul></li><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M4.5 4.5h12l3 3v8h-15z"/><path d="M2.5 20h19L20 15.5H4z" fill="currentColor" opacity="0.3" stroke="none"/><path d="M2.5 20h19L20 15.5H4z"/></svg></span>Process & System</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/environment-variables" data-link="" data-prefetch="hover">Environment Variables</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/shell" data-link="" data-prefetch="hover">Shell</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/child-process" data-link="" data-prefetch="hover">Spawn</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/webview" data-link="" data-prefetch="hover">WebView</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/cron" data-link="" data-prefetch="hover">Cron</a></li></ul></li><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M3 7h4.5V3h5v4H17v4.5h4v5h-4V21h-5v-4H8v4H3z"/></svg></span>Interop & Tooling</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/node-api" data-link="" data-prefetch="hover">Node-API</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/ffi" data-link="" data-prefetch="hover">FFI</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/c-compiler" data-link="" data-prefetch="hover">C Compiler</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/transpiler" data-link="" data-prefetch="hover">Transpiler</a></li></ul></li><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M18 3l-3 3 3 3 3-3v4.5l-3 3h-4.5L6 21l-3-3 7.5-7.5V6l3-3z"/></svg></span>Utilities</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/csrf" data-link="" data-prefetch="hover">CSRF Protection</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/secrets" data-link="" data-prefetch="hover">Secrets</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/console" data-link="" data-prefetch="hover">Console</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/toml" data-link="" data-prefetch="hover">TOML</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/yaml" data-link="" data-prefetch="hover">YAML</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/markdown" data-link="" data-prefetch="hover">Markdown</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/json5" data-link="" data-prefetch="hover">JSON5</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/xml" data-link="" data-prefetch="hover">XML</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/jsonl" data-link="" data-prefetch="hover">JSONL</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/html-rewriter" data-link="" data-prefetch="hover">HTMLRewriter</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/image" data-link="" data-prefetch="hover">Image</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/hashing" data-link="" data-prefetch="hover">Hashing</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/glob" data-link="" data-prefetch="hover">Glob</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/semver" data-link="" data-prefetch="hover">Semver</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/color" data-link="" data-prefetch="hover">Color</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/utils" data-link="" data-prefetch="hover">Utils</a></li></ul></li><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M8 3h8l5 5v8l-5 5H8l-5-5V8z"/><path d="M7.5 12l3 3 6-6"/></svg></span>Standards & Compatibility</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/globals" data-link="" data-prefetch="hover">Globals</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/bun-apis" data-link="" data-prefetch="hover">Bun APIs</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/web-apis" data-link="" data-prefetch="hover">Web APIs</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/runtime/nodejs-compat" data-link="" data-prefetch="hover">Node.js Compatibility</a></li></ul></li><li><p class="mb-2 flex items-center gap-2 text-[13px] font-semibold text-fg"><span aria-hidden="true" class="inline-flex shrink-0 items-center justify-center [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 text-fg-faint"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M12 20.5L3 11.5V7l3.5-3.5H9l3 3 3-3h2.5L21 7v4.5z"/></svg></span>Contributing</p><ul class="border-l border-line"><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/project/roadmap" data-link="" data-prefetch="hover">Roadmap</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/project/benchmarking" data-link="" data-prefetch="hover">Benchmarking</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/project/contributing" data-link="" data-prefetch="hover">Contributing</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/project/building-windows" data-link="" data-prefetch="hover">Building Windows</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/project/bindgen" data-link="" data-prefetch="hover">Bindgen</a></li><li><a class="-ml-px block border-l py-[5px] pl-4 pr-2 text-[14px] leading-snug transition-colors border-transparent text-fg-muted hover:border-line-strong hover:text-fg" href="/docs/project/lice
1nse" data-link="" data-prefetch="hover">License</a></li></ul></li></ul></nav>
1<script>try{var r=document.currentScript.parentElement,k="rail:docs",v=sessionStorage.getItem(k);if(v)r.scrollTop=+v;r.addEventListener("scroll",function(){sessionStorage.setItem(k,r.scrollTop)},{passive:true})}catch(e){}</script>
1</aside><div class="min-w-0 flex-auto px-gutter py-10 md:px-10 lg:px-14"><div class="grid gap-12"><article id="docs-content" class="min-w-0 max-w-3xl mx-auto w-full"><header class="mb-8"><div class="flex items-start justify-between gap-4"><nav aria-label="Breadcrumb" class="mb-3"><ol class="flex flex-wrap items-center gap-x-1.5 gap-y-1 text-[13px] font-medium text-fg-faint"><li class="flex items-center gap-1.5"><a class="text-fg-muted transition-colors hover:text-fg" href="/docs" data-link="" data-prefetch="true">Runtime</a></li><li class="flex items-center gap-1.5"><span aria-hidden="true" class="text-fg-faint/70">âº</span><span class="text-accent-strong">Get Started</span></li></ol></nav><div class="relative inline-flex text-[13px] -mt-1 hidden shrink-0 sm:inline-flex"><button type="button" class="relative inline-flex h-8 items-center gap-2 border border-line px-2.5 text-fg-muted transition-colors hover:z-10 hover:border-rule hover:text-fg"><span class="t-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M5.5 16H3V3h13v2.5"/><path d="M8 8h9l4 4v9H8z"/></svg></span>Copy page</button><button type="button" aria-label="More page actions" aria-haspopup="menu" aria-expanded="false" class="-ml-px inline-flex h-8 w-8 items-center justify-center border border-line text-fg-muted transition-colors hover:z-10 hover:border-rule hover:text-fg"><span class="t-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 transition-transform" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M6 9l6 6 6-6"/></svg></span></button></div></div><h1 class="display text-balance text-[clamp(1.9rem,4vw,2.6rem)] font-bold leading-[1.08] tracking-tight text-fg">Welcome to Bun</h1><p class="mt-3 max-w-[64ch] text-pretty text-[1.05rem] leading-relaxed text-fg-muted">Bun is an all-in-one toolkit for developing modern JavaScript/TypeScript applications.</p></header><div class="DocSearch-content docs-prose prose w-full max-w-none" style="--tw-prose-body:rgb(var(--c-fg) / 0.88);--tw-prose-headings:rgb(var(--c-fg));--tw-prose-lead:rgb(var(--c-fg-muted));--tw-prose-links:rgb(var(--c-fg));--tw-prose-bold:rgb(var(--c-fg));--tw-prose-counters:rgb(var(--c-fg-faint));--tw-prose-bullets:rgb(var(--c-line-strong));--tw-prose-hr:rgb(var(--c-line));--tw-prose-quotes:rgb(var(--c-fg));--tw-prose-quote-borders:rgb(var(--c-line-strong));--tw-prose-captions:rgb(var(--c-fg-faint));--tw-prose-kbd:rgb(var(--c-fg));--tw-prose-kbd-shadows:var(--c-fg);--tw-prose-code:rgb(var(--c-fg));--tw-prose-pre-code:rgb(var(--c-code-fg));--tw-prose-pre-bg:rgb(var(--c-code-bg));--tw-prose-th-borders:rgb(var(--c-line-strong));--tw-prose-td-borders:rgb(var(--c-line))"><div class="card-group not-prose my-6 grid gap-4 grid-cols-1 sm:grid-cols-2 [&>.doc-card-wrap]:my-0 [&>.doc-card-wrap]:h-full"><div class="doc-card-wrap not-prose my-4"><a href="/docs/runtime" class="doc-card card group/card relative flex h-full flex-col overflow-hidden rounded-xl border border-line bg-surface text-left font-normal text-fg no-underline transition-colors hover:border-accent/70 focus-visible:border-accent"><div class="relative flex h-full px-5 py-4 flex-col gap-2.5"><span class="doc-card-icon inline-flex shrink-0 text-accent"><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-[22px] w-[22px]" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><polygon points="10.5,6 10.5,3 13.5,3 13.5,6 14.5,6 15,6.5 17,4.5 19.5,7 17.5,9 18,9.5 18,10.5 21,10.5 21,13.5 18,13.5 18,14.5 17.5,15 19.5,17 17,19.5 15,17.5 14.5,18 13.5,18 13.5,21 10.5,21 10.5,18 9.5,18 9,17.5 7,19.5 4.5,17 6.5,15 6,14.5 6,13.5 3,13.5 3,10.5 6,10.5 6,9.5 6.5,9 4.5,7 7,4.5 9,6.5 9.5,6"/><rect x="9.5" y="9.5" width="5" height="5"/></svg></span></span><div class="flex min-w-0 flex-1 flex-col"><p class="doc-card-title m-0 text-[15px] font-semibold leading-snug text-fg">
1Bun Runtime</p><div class="doc-card-body text-[14px] leading-relaxed text-fg-muted mt-1 [&_p]:my-0 [&_p+p]:mt-2 [&_strong]:font-semibold [&_strong]:text-fg [&_ul]:my-1 [&_ul]:list-disc [&_ul]:pl-5 [&_code]:rounded [&_code]:border [&_code]:border-line [&_code]:bg-code-bg [&_code]:px-[0.3em] [&_code]:py-[0.05em] [&_code]:font-mono [&_code]:text-[0.86em] [&_code]:text-fg"><p>A fast JavaScript runtime designed as a drop-in replacement for Node.js</p></div><div class="mt-auto pt-4"><span class="inline-flex items-center gap-1.5 text-[13.5px] font-medium text-fg-muted transition-colors group-hover/card:text-accent-strong [&_code]:font-mono [&_code]:text-[0.92em]"><span>Get started with <code>bun run</code></span><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 transition-transform duration-150 group-hover/card:translate-x-0.5" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M4 12h14"/><path d="M13 6l6 6-6 6"/></svg></span></span></div></div></div></a></div><div class="doc-card-wrap not-prose my-4"><a href="/docs/pm/cli/install" class="doc-card card group/card relative flex h-full flex-col overflow-hidden rounded-xl border border-line bg-surface text-left font-normal text-fg no-underline transition-colors hover:border-accent/70 focus-visible:border-accent"><div class="relative flex h-full px-5 py-4 flex-col gap-2.5"><span class="doc-card-icon inline-flex shrink-0 text-accent"><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-[22px] w-[22px]" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M12 2.5l9 4.5v10l-9 4.5-9-4.5V7z"/><path d="M4 7.5l8 4 8-4M12 11.5V21"/><path d="M12 2.5l9 4.5-9 4.5L3 7z" fill="currentColor" opacity="0.3" stroke="none"/></svg></span></span><div class="flex min-w-0 flex-1 flex-col"><p class="doc-card-title m-0 text-[15px] font-semibold leading-snug text-fg">Bun Package Manager</p><div class="doc-card-body text-[14px] leading-relaxed text-fg-muted mt-1 [&_p]:my-0 [&_p+p]:mt-2 [&_strong]:font-semibold [&_strong]:text-fg [&_ul]:my-1 [&_ul]:list-disc [&_ul]:pl-5 [&_code]:rounded [&_code]:border [&_code]:border-line [&_code]:bg-code-bg [&_code]:px-[0.3em] [&_code]:py-[0.05em] [&_code]:font-mono [&_code]:text-[0.86em] [&_code]:text-fg"><p>Install packages up to 30x faster than npm with a global cache and workspaces</p></div><div class="mt-auto pt-4"><span class="inline-flex items-center gap-1.5 text-[13.5px] font-medium text-fg-muted transition-colors group-hover/card:text-accent-strong [&_code]:font-mono [&_code]:text-[0.92em]"><span>Get started with <code>bun install</code></span><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 transition-transform duration-150 group-hover/card:translate-x-0.5" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M4 12h14"/><path d="M13 6l6 6-6 6"/></svg></span></span></div></div></div></a></div><div class="doc-card-wrap not-prose my-4"><a href="/docs/test" class="doc-card card group/card relative flex h-full flex-col overflow-hidden rounded-xl border border-line bg-surface text-left font-normal text-fg no-underline transition-colors hover:border-accent/70 focus-visible:border-accent"><div class="relative flex h-full px-5 py-4 flex-col gap-2.5"><span class="doc-card-icon inline-flex shrink-0 text-accent"><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-[22px] w-[22px]" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M8.5 3h7"/><path d="M10 3v5L4 20h16L14 8V3"/><path d="M7 14h10l3 6H4z" fill="currentColor" opacity="0.3" stroke="none"/><path d="M7.5 14h9"/></svg></span></span><div class="flex min-w-0 flex-1 flex-col"><p class="doc-card-title m-0 text-[15px] font-semibold leading-snug text-fg">Bun Test Runner</p><div class="doc-card-body text-[14px] leading-relaxed text-fg-muted mt-1 [&_p]:my-0 [&_p+p]:mt-2 [&_strong]:font-semibold [&_strong]:text-fg [&_ul]:my-1 [&_ul]:list-disc [&_ul]:pl-5 [&_code]:rounded [&_code]:border [&_code]:border-line [&_code]:bg-code-bg [&_code]:px-[0.3em] [&_code]:py-[0.05em] [&_code]:font-mono [&_code]:text-[0.86em] [&_code]:text-fg"><p>Jest-compatible, TypeScript-first tests with snapshots, DOM, and watch mode</p></div><div class="mt-auto pt-4"><span class="inline-flex items-center gap-1.5 text-[13.5px] font-medium text-fg-muted transition-colors group-hover/card:text-accent-strong [&_code]:font-mono [&_code]:text-[0.92em]"><span>Get started with <code>bun test</code></span><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 transition-transform duration-150 group-hover/card:translate-x-0.5" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M4 12h14"/><path d="M13 6l6 6-6 6"/></svg></span></span></div></div></div></a></div><div class="doc-card-wrap not-prose my-4"><a href="/docs/bundler" class="doc-card card group/card relative flex h-full flex-col overflow-hidden rounded-xl border border-line bg-surface text-left font-normal text-fg no-underline transition-colors hover:border-accent/70 focus-visible:border-accent"><div class="relative flex h-full px-5 py-4 flex-col gap-2.5">
1<span class="doc-card-icon inline-flex shrink-0 text-accent"><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-[22px] w-[22px]" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M9 3h8l4 4v10H9z" fill="currentColor" opacity="0.3" stroke="none"/><path d="M9 3h8l4 4v10H9z"/><path d="M6 6.5V20h11"/><path d="M3 8v13h11"/></svg></span></span><div class="flex min-w-0 flex-1 flex-col"><p class="doc-card-title m-0 text-[15px] font-semibold leading-snug text-fg">Bun Bundler</p><div class="doc-card-body text-[14px] leading-relaxed text-fg-muted mt-1 [&_p]:my-0 [&_p+p]:mt-2 [&_strong]:font-semibold [&_strong]:text-fg [&_ul]:my-1 [&_ul]:list-disc [&_ul]:pl-5 [&_code]:rounded [&_code]:border [&_code]:border-line [&_code]:bg-code-bg [&_code]:px-[0.3em] [&_code]:py-[0.05em] [&_code]:font-mono [&_code]:text-[0.86em] [&_code]:text-fg"><p>Bundle TypeScript, JSX, React & CSS for both browsers and servers</p></div><div class="mt-auto pt-4"><span class="inline-flex items-center gap-1.5 text-[13.5px] font-medium text-fg-muted transition-colors group-hover/card:text-accent-strong [&_code]:font-mono [&_code]:text-[0.92em]"><span>Get started with <code>bun build</code></span><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-3.5 w-3.5 transition-transform duration-150 group-hover/card:translate-x-0.5" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M4 12h14"/><path d="M13 6l6 6-6 6"/></svg></span></span></div></div></div></a></div></div><hr/><h2 id="get-started" class="anchored">Get Started<a href="#get-started" aria-label="Permalink" data-pagefind-ignore="" class="anchor">#</a></h2><p>Bun ships as a single, dependency-free binary and includes a runtime, package manager, test runner, and bundler. New to Bun?</p><div class="card-group not-prose my-6 grid gap-4 grid-cols-1 sm:grid-cols-2 [&>.doc-card-wrap]:my-0 [&>.doc-card-wrap]:h-full"><div class="doc-card-wrap not-prose my-4"><a href="/docs/installation" class="doc-card card group/card relative flex h-full flex-col overflow-hidden rounded-xl border border-line bg-surface text-left font-normal text-fg no-underline transition-colors hover:border-accent/70 focus-visible:border-accent"><div class="relative flex h-full px-5 py-4 flex-col gap-2.5"><span class="doc-card-icon inline-flex shrink-0 text-accent"><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-[22px] w-[22px]" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M12 3v11"/><path d="M6.5 9.5L12 15l5.5-5.5"/><path d="M3 14v6h18v-6"/></svg></span></span><div class="flex min-w-0 flex-1 flex-col"><p class="doc-card-title m-0 text-[15px] font-semibold leading-snug text-fg">Install Bun</p><div class="doc-card-body text-[14px] leading-relaxed text-fg-muted mt-1 [&_p]:my-0 [&_p+p]:mt-2 [&_strong]:font-semibold [&_strong]:text-fg [&_ul]:my-1 [&_ul]:list-disc [&_ul]:pl-5 [&_code]:rounded [&_code]:border [&_code]:border-line [&_code]:bg-code-bg [&_code]:px-[0.3em] [&_code]:py-[0.05em] [&_code]:font-mono [&_code]:text-[0.86em] [&_code]:text-fg"><p>Supported platforms and all install methods.</p></div></div></div></a></div><div class="doc-card-wrap not-prose my-4"><a href="/docs/quickstart" class="doc-card card group/card relative flex h-full flex-col overflow-hidden rounded-xl border border-line bg-surface text-left font-normal text-fg no-underline transition-colors hover:border-accent/70 focus-visible:border-accent"><div class="relative flex h-full px-5 py-4 flex-col gap-2.5">
1<span class="doc-card-icon inline-flex shrink-0 text-accent"><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-[22px] w-[22px]" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M13 3L5 13h6l-1 8 9-10h-6z"/></svg></span></span><div class="flex min-w-0 flex-1 flex-col"><p class="doc-card-title m-0 text-[15px] font-semibold leading-snug text-fg">Quickstart</p><div class="doc-card-body text-[14px] leading-relaxed text-fg-muted mt-1 [&_p]:my-0 [&_p+p]:mt-2 [&_strong]:font-semibold [&_strong]:text-fg [&_ul]:my-1 [&_ul]:list-disc [&_ul]:pl-5 [&_code]:rounded [&_code]:border [&_code]:border-line [&_code]:bg-code-bg [&_code]:px-[0.3em] [&_code]:py-[0.05em] [&_code]:font-mono [&_code]:text-[0.86em] [&_code]:text-fg"><p>Hello world in minutes with Bun.serve.</p></div></div></div></a></div></div><hr/><h2 id="what-s-inside" class="anchored">What's Inside<a href="#what-s-inside" aria-label="Permalink" data-pagefind-ignore="" id="whats-inside" class="anchor">#</a></h2><ul><li>Runtime: Execute JavaScript/TypeScript files and package scripts with near-zero overhead.</li><li>Package Manager: Fast installs, workspaces, overrides, and audits with <code>bun install</code>.</li><li>Test Runner: Jest-compatible, TypeScript-first tests with snapshots, DOM, and watch mode.</li><li>Bundler: Native bundling for JS/TS/JSX with splitting, plugins, and HTML imports.</li></ul><p>Explore each area using the cards above. Each section is structured with an overview, short examples, reference, and best practices for fast scanning and deep dives.</p><hr/><h2 id="what-is-bun" class="anchored">What is Bun?<a href="#what-is-bun" aria-label="Permalink" data-pagefind-ignore="" class="anchor">#</a></h2><p>Bun is an all-in-one toolkit for JavaScript and TypeScript apps. It ships as a single executable called <code>bun</code>.</p><p>At its core is the <em>Bun runtime</em>, a fast JavaScript runtime designed as <strong>a drop-in replacement for Node.js</strong>. It's written in Rust and powered by JavaScriptCore, reducing startup time and memory usage.</p><div class="DocFence group/fence relative my-5 overflow-hidden rounded-lg border border-line bg-code-bg text-code-fg [&:has(+.DocFence-output)]:rounded-b-none" data-lang="bash"><div class="DocFenceHeader flex min-h-[34px] items-center gap-2 border-b border-line bg-subtle/70 px-3.5 py-1.5 font-mono text-[12px] leading-none text-fg-muted"><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-4 w-4 shrink-0" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M3 4h14l4 4v12H3z"/><path d="M7 10l3 3-3 3"/><path d="M12.5 16H17"/></svg></span><span class="truncate" translate="no">terminal</span></div><div class="relative" style="--doc-prompt:"$ ""><div class="CodeBlock group/code !my-0 !rounded-none !border-0 [&_pre]:!overflow-x-visible [&_.line-hl]:inline-block [&_.line-hl]:min-w-[calc(100%+4.1rem)] [&_.line-hl]:-ml-[1.1rem] [&_.line-hl]:pl-[calc(1.1rem-3px)] [&_.line-hl]:pr-12 [&_.line-hl]:align-top [&_.line-hl]:h-5 [&_.line-hl]:border-l-[3px] [&_.line-hl]:border-accent [&_.line-hl]:bg-accent/[0.09] [&_.line:not(:empty):has(span)]:before:content-[var(--doc-prompt)] [&_.line]:before:select-none [&_.line]:before:text-fg-faint [&_.line:has(>.s-6272a4:first-child)]:before:content-none"><div class="relative"><div class="CodeBlockScroll"><div data-h="0"><pre class="shiki"><code><span class="line"><span class="s-f8f8f2">bun run index.tsx </span><span class="s-6272a4"># TS and JSX supported by default</span></span></code></pre></div></div><button type="button" aria-label="Copy to clipboard" class="CopyIcon group/copy inline-flex items-center justify-center rounded-md text-fg-faint transition-[color,background,opacity] hover:bg-fg/[0.06] hover:text-fg h-7 w-7 copy absolute right-1.5 top-[-3px]"><span class="relative block h-4 w-4"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter" aria-hidden="true" class="absolute inset-0 h-4 w-4 transition-[opacity,transform] duration-200 opacity-100"><path d="M5.5 16H3V3h13v2.5"></path><path d="M8 8h9l4 4v9H8z"></path></svg><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter" aria-hidden="true" class="absolute inset-0 h-4 w-4 text-success transition-[opacity,transform] duration-200 scale-75 opacity-0"><path d="M4 12l5 5L20 6"></path></svg></span></button></div></div></div></div><p>The <code>bun</code> command-line tool also implements a test runner, script runner, and Node.js-compatible package manager. All three are significantly faster than existing tools, and you can use them in existing Node.js projects with little to no changes.</p><div class="DocFence group/fence relative my-5 overflow-hidden rounded-lg border border-line bg-code-bg text-code-fg [&:has(+.DocFence-output)]:rounded-b-none" data-lang="bash"><div class="DocFenceHeader flex min-h-[34px] items-center gap-2 border-b border-line bg-subtle/70 px-3.5 py-1.5 font-mono text-[12px] leading-none text-fg-muted"><span class="doc-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-4 w-4 shrink-0" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M3 4h14l4 4v12H3z"/><path d="M7 10l3 3-3 3"/><path d="M12.5 16H17"/></svg></span><span class="truncate" translate="no">terminal</span></div><div class="relative" style="--doc-prompt:"$ ""><div class="CodeBlock group/code !my-0 !rounded-none !border-0 [&_pre]:!overflow-x-visible [&_.line-hl]:inline-block [&_.line-hl]:min-w-[calc(100%+4.1rem)] [&_.line-hl]:-ml-[1.1rem] [&_.line-hl]:pl-[calc(1.1rem-3px)] [&_.line-hl]:pr-12 [&_.line-hl]:align-top [&_.line-hl]:h-5 [&_.line-hl]:border-l-[3px] [&_.line-hl]:border-accent [&_.line-hl]:bg-accent/[0.09] [&_.line:not(:empty):has(span)]:before:content-[var(--doc-prompt)] [&_.line]:before:select-none [&_.line]:before:text-fg-faint [&_.line:has(>
1.s-6272a4:first-child)]:before:content-none"><div class="relative"><div class="CodeBlockScroll"><div data-h="1"><pre class="shiki"><code><span class="line"><span class="s-f8f8f2">bun run start </span><span class="s-6272a4"># run the `start` script</span></span> 2<span class="line"><span class="s-f8f8f2">bun install </span><span class="s-ff79c6"><</span><span class="s-f8f8f2">pkg</span><span class="s-ff79c6">></span><span class="s-f8f8f2"> </span><span class="s-6272a4"># install a package</span></span> 3<span class="line"><span class="s-f8f8f2">bun build ./index.tsx </span><span class="s-6272a4"># bundle a project for browsers</span></span> 4<span class="line"><span class="s-f8f8f2">bun </span><span class="s-8be9fd">test</span><span class="s-f8f8f2"> </span><span class="s-6272a4"># run tests</span></span> 5<span class="line"><span class="s-f8f8f2">bunx cowsay </span><span class="s-e9f284">'</span><span class="s-f1fa8c">Hello, world!</span><span class="s-e9f284">'</span><span class="s-f8f8f2"> </span><span class="s-6272a4"># execute a package</span></span></code></pre></div></div><button type="button" aria-label="Copy to clipboard" class="CopyIcon group/copy inline-flex items-center justify-center rounded-md text-fg-faint transition-[color,background,opacity] hover:bg-fg/[0.06] hover:text-fg h-7 w-7 copy absolute right-1.5 top-[-3px]"><span class="relative block h-4 w-4"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter" aria-hidden="true" class="absolute inset-0 h-4 w-4 transition-[opacity,transform] duration-200 opacity-100"><path d="M5.5 16H3V3h13v2.5"></path><path d="M8 8h9l4 4v9H8z"></path></svg><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter" aria-hidden="true" class="absolute inset-0 h-4 w-4 text-success transition-[opacity,transform] duration-200 scale-75 opacity-0"><path d="M4 12l5 5L20 6"></path></svg></span></button></div></div></div></div><h2 id="what-is-a-runtime" class="anchored">What is a runtime?<a href="#what-is-a-runtime" aria-label="Permalink" data-pagefind-ignore="" class="anchor">#</a></h2><p>JavaScript (or, more formally, ECMAScript) is only a <em>specification</em> for a programming language. Anyone can write a JavaScript <em>engine</em> that ingests a valid JavaScript program and executes it. The two most popular engines in use today are V8 (developed by Google) 6and JavaScriptCore (developed by Apple). Both are open source.</p><p>But most JavaScript programs don't run in a vacuum. They need a way to access the outside world to perform useful tasks. This is where <em>runtimes</em> come in. They implement additional APIs and make them available to the JavaScript programs they execute.</p><h3 id="browsers" class="anchored">Browsers<a href="#browsers" aria-label="Permalink" data-pagefind-ignore="" class="anchor">#</a></h3><p>Browsers ship with JavaScript runtimes that implement a set of Web-specific APIs, exposed on the global <code>window</code> object. Any JavaScript code executed by the browser can use these APIs to add interactive or dynamic behavior to the current webpage.</p><h3 id="node-js" class="anchored">Node.js<a href="#node-js" aria-label="Permalink" data-pagefind-ignore="" id="nodejs" class="anchor">#</a></h3><p>Node.js is a JavaScript runtime for non-browser environments, like servers. JavaScript programs executed by Node.js have access to a set of Node.js-specific <a href="https://nodejs.org/api/globals.html" target="_blank" rel="noopener noreferrer">globals</a> like <code>Buffer</code>, <code>process</code>, and <code>__dirname</code> in addition to built-in modules for OS-level tasks like reading/writing files (<code>node:fs</code>) and networking (<code>node:net</code>, <code>node:http</code>). Node.js also implements a CommonJS-based module system and resolution algorithm that pre-dates JavaScript's native module system.</p><p>Bun is designed as a faster, leaner, more modern replacement for Node.js.</p><h2 id="design-goals" class="anchored">Design goals<a href="#design-goals" aria-label="Permalink" data-pagefind-ignore="" class="anchor">#</a></h2><p>Bun is designed from the ground-up with today'
6s JavaScript ecosystem in mind.</p><ul><li><strong>Speed</strong>. Bun processes start <a href="https://twitter.com/jarredsumner/status/1499225725492076544" target="_blank" rel="noopener noreferrer">4x faster than Node.js</a>.</li><li><strong>TypeScript & JSX support</strong>. You can directly execute <code>.jsx</code>, <code>.ts</code>, and <code>.tsx</code> files; Bun's transpiler converts these to vanilla JavaScript before execution.</li><li><strong>ESM & CommonJS compatibility</strong>. The world is moving towards ES modules (ESM), but millions of packages on npm still require CommonJS. Bun recommends ES modules, but supports CommonJS.</li><li><strong>Web-standard APIs</strong>. Bun implements standard Web APIs like <code>fetch</code>, <code>WebSocket</code>, and <code>ReadableStream</code>. Bun is powered by the JavaScriptCore engine, which is developed by Apple for Safari, so some APIs like <a href="https://developer.mozilla.org/en-US/docs/Web/API/Headers" target="_blank" rel="noopener noreferrer"><code>Headers</code></a> and <a href="https://developer.mozilla.org/en-US/docs/Web/API/URL" target="_blank" rel="noopener noreferrer"><code>URL</code></a> directly use <a href="https://github.com/oven-sh/bun/blob/HEAD/src/jsc/bindings/webcore/JSFetchHeaders.cpp" target="_blank" rel="noopener noreferrer">Safari's implementation</a>.</li><li><strong>Node.js compatibility</strong>. In addition to supporting Node-style module resolution, Bun aims for full compatibility with built-in Node.js globals (<code>process</code>, <code>Buffer</code>) and modules (<code>path</code>, <code>fs</code>, <code>http</code>). <em>This is an ongoing effort.</em> See <a href="/docs/runtime/nodejs-compat">Node.js compatibility</a> for the current status.</li></ul><p>Bun is more than a runtime. The long-term goal is a cohesive, infrastructural toolkit for building apps with JavaScript/TypeScript: a package manager, transpiler, bundler, script runner, and test runner.</p></div><footer class="mt-16 flex flex-col gap-8"><nav aria-label="Pagination" data-pagefind-ignore="true" class="grid gap-4 sm:grid-cols-2"><span></span><a class="group/n flex flex-col gap-1 rounded-2xl border border-line bg-surface p-4 transition-colors hover:border-line-strong items-end text-right" href="/docs/installation" data-link="" data-prefetch="true"><span class="label">Next</span><span class="flex items-center gap-2 text-[15px] font-medium text-fg"><span class="min-w-0">Installation</span><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter" aria-hidden="true" class="h-4 w-4 shrink-0 transition-transform group-hover/n:translate-x-0.5"><path d="M4 12h14"></path><path d="M13 6l6 6-6 6"></path></svg></span></a></nav><div class="flex flex-wrap items-center justify-between gap-4 border-t border-line pt-6 text-[13.5px] text-fg-faint"><a href="https://github.com/oven-sh/bun/blob/main/docs/index.mdx" target="_blank" rel="noopener" class="inline-flex items-center gap-2 text-fg-muted transition-colors hover:text-fg"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter" aria-hidden="true" class="h-4 w-4"><path d="M9.5 21v-3.5l1-1.5C7 15.5 5 14 5 10.5L6.5 8 6 4.5l3.5 1.5h5l3.5-1.5-.5 3.5 1.5 2.5c0 3.5-2 5-5.5 5.5l1 1.5V21"></path><path d="M9.5 18.5H7l-1.5-2L4 15.5"></path><rect x="8.5" y="9.75" width="1.75" height="2.25" fill="currentColor" stroke="none"></rect><rect x="13.75" y="9.75" width="1.75" height="2.25" fill="currentColor" stroke="none"></rect></svg>Edit this page on GitHub</a><a href="/docs.md" class="mono text-[12px] uppercase tracking-[0.12em] transition-colors hover:text-fg">View as Markdown</a></div></footer></article></div></div></div></main><button type="button" aria-label="Ask AI about Bun" class="ask-fab fixed bottom-4 right-4 z-[110] inline-flex h-10 items-center gap-2 border border-rule bg-canvas px-3.5 text-[13.5px] font-medium text-fg shadow-[0_2px_10px_rgba(0,0,0,0.12)] transition-colors hover:bg-subtle print:hidden"><span class="t-icon inline-flex shrink-0 [&>svg]:h-full [&>svg]:w-full h-4 w-4" aria-hidden="true"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="square" stroke-linejoin="miter"><path d="M9 7l2 4.5 4.5 2-4.5 2L9 20l-2-4.5-4.5-2L7 11.5z"/><path d="M18 2l1.25 2.75L22 6l-2.75 1.25L18 10l-1.25-2.75L14 6l2.75-1.25z" fill="currentColor" stroke="none"/><path d="M18.5 16.5v4M16.5 18.5h4"/></svg></span>Ask AI</button></div></div>
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