Single-file executable

Bun's bundler implements a --compile flag for generating a standalone binary from a TypeScript or JavaScript file.

terminal

bun build ./cli.ts --compile --outfile mycli

build.ts

await Bun.build({
  entrypoints: ["./cli.ts"],
  compile: {
    outfile: "./mycli",
  },
});

cli.ts

console.log("Hello world!");

Bun bundles cli.ts into an executable you can run directly:

terminal

./mycli

Hello world!

Bun bundles all imported files and packages into the executable, along with a copy of the Bun runtime. All built-in Bun and Node.js APIs are supported.

Cross-compile to other platforms#

Use the --target flag to compile your standalone executable for a different operating system, architecture, or version of Bun than the machine you're running bun build on.

To build for Linux x64 (most servers):

terminal

bun build --compile --target=bun-linux-x64 ./index.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./index.ts"],
  compile: {
    target: "bun-linux-x64",
    outfile: "./myapp",
  },
});

To build for Linux ARM64 (for example, Graviton or Raspberry Pi):

terminal

# Note: the default architecture is x64 if no architecture is specified.
bun build --compile --target=bun-linux-arm64 ./index.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./index.ts"],
  compile: {
    target: "bun-linux-arm64",
    outfile: "./myapp",
  },
});

To build for Windows x64:

terminal

bun build --compile --target=bun-windows-x64 ./path/to/my/app.ts --outfile myapp

# note: if no .exe extension is provided, Bun adds it automatically for Windows executables

build.ts

await Bun.build({
  entrypoints: ["./path/to/my/app.ts"],
  compile: {
    target: "bun-windows-x64",
    outfile: "./myapp", // .exe added automatically
  },
});

To build for Windows arm64:

terminal

bun build --compile --target=bun-windows-arm64 ./path/to/my/app.ts --outfile myapp

# note: if no .exe extension is provided, Bun adds it automatically for Windows executables

build.ts

await Bun.build({
  entrypoints: ["./path/to/my/app.ts"],
  compile: {
    target: "bun-windows-arm64",
    outfile: "./myapp", // .exe added automatically
  },
});

To build for macOS arm64:

terminal

bun build --compile --target=bun-darwin-arm64 ./path/to/my/app.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./path/to/my/app.ts"],
  compile: {
    target: "bun-darwin-arm64",
    outfile: "./myapp",
  },
});

To build for macOS x64:

terminal

bun build --compile --target=bun-darwin-x64 ./path/to/my/app.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./path/to/my/app.ts"],
  compile: {
    target: "bun-darwin-x64",
    outfile: "./myapp",
  },
});

Supported targets#

The segments of the --target value can appear in any order, as long as they're delimited by -.

--target	Operating System	Architecture	Libc
bun-linux-x64	Linux	x64	glibc
bun-linux-arm64	Linux	arm64	glibc
bun-windows-x64	Windows	x64	-
bun-windows-arm64	Windows	arm64	-
bun-darwin-x64	macOS	x64	-
bun-darwin-arm64	macOS	arm64	-
bun-linux-x64-musl	Linux	x64	musl
bun-linux-arm64-musl	Linux	arm64	musl

On x64, Bun ships a single binary that targets Nehalem (SSE4.2) and selects AVX2/AVX-512 code paths at runtime. The -baseline and -modern target suffixes are still accepted for backward compatibility and resolve to the same binary; you do not need to pick one based on the destination CPU.

Build-time constants#

Use the --define flag to inject build-time constants into your executable, such as version numbers, build timestamps, or configuration values:

terminal

bun build --compile --define BUILD_VERSION='"1.2.3"' --define BUILD_TIME='"2024-01-15T10:30:00Z"' src/cli.ts --outfile mycli

build.ts

await Bun.build({
  entrypoints: ["./src/cli.ts"],
  compile: {
    outfile: "./mycli",
  },
  define: {
    BUILD_VERSION: JSON.stringify("1.2.3"),
    BUILD_TIME: JSON.stringify("2024-01-15T10:30:00Z"),
  },
});

Bun inlines these constants into the binary at build time, so they cost nothing at runtime and enable dead code elimination.

For more examples and patterns, see the Build-time constants guide.

Deploying to production#

Compiled executables reduce memory usage and improve Bun's start time.

Normally, Bun reads and transpiles JavaScript and TypeScript files on import and require. This is part of what makes so much of Bun "just work", but it's not free: reading files from disk, resolving paths, parsing, transpiling, and printing source code costs time and memory.

Compiled executables move that cost from runtime to build time.

When deploying to production, we recommend the following:

terminal

bun build --compile --minify --sourcemap ./path/to/my/app.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./path/to/my/app.ts"],
  compile: {
    outfile: "./myapp",
  },
  minify: true,
  sourcemap: "linked",
});

Bytecode compilation#

To improve startup time, enable bytecode compilation:

terminal

bun build --compile --minify --sourcemap --bytecode ./path/to/my/app.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./path/to/my/app.ts"],
  compile: {
    outfile: "./myapp",
  },
  minify: true,
  sourcemap: "linked",
  bytecode: true,
});

Using bytecode compilation, tsc starts 2x faster:

Bytecode compilation moves parsing overhead for large input files from runtime to bundle time. Your app starts faster, in exchange for making the bun build command a little slower. Bytecode compilation doesn't obscure source code.

Bytecode compilation supports both cjs and esm formats when used with --compile.

What do these flags do?#

The --minify argument reduces the size of the transpiled output code. For a large application, this can save megabytes of space. For smaller applications, it might still improve start time a little.

The --sourcemap argument embeds a sourcemap compressed with zstd, so that errors & stacktraces point to their original locations instead of the transpiled location. Bun decompresses & resolves the sourcemap automatically when an error occurs.

The --bytecode argument enables bytecode compilation. Every time you run JavaScript code in Bun, JavaScriptCore (the engine) compiles your source code into bytecode. --bytecode moves that parsing work from runtime to bundle time, which shortens startup.

Embedding runtime arguments#

--compile-exec-argv="args" - Embed runtime arguments, available at runtime in process.execArgv:

terminal

bun build --compile --compile-exec-argv="--smol --user-agent=MyBot" ./app.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./app.ts"],
  compile: {
    execArgv: ["--smol", "--user-agent=MyBot"],
    outfile: "./myapp",
  },
});

app.ts

// In the compiled app
console.log(process.execArgv); // ["--smol", "--user-agent=MyBot"]

Runtime arguments via `BUN_OPTIONS`#

Standalone executables read the BUN_OPTIONS environment variable, so you can pass runtime flags without recompiling:

terminal

# Enable CPU profiling on a compiled executable
BUN_OPTIONS="--cpu-prof" ./myapp

# Enable heap profiling with markdown output
BUN_OPTIONS="--heap-prof-md" ./myapp

# Combine multiple flags
BUN_OPTIONS="--smol --cpu-prof-md" ./myapp

Automatic config loading#

Standalone executables can automatically load configuration files from the directory where they are run. By default:

tsconfig.json and package.json loading is disabled — these are typically only needed at development time, and the bundler already uses them when compiling
.env and bunfig.toml loading is enabled — these often contain runtime configuration that may vary per deployment

In a future version of Bun, .env and bunfig.toml may also be disabled by default for more deterministic behavior.

Enabling config loading at runtime#

If your executable needs to read tsconfig.json or package.json at runtime, opt in with these flags:

terminal

# Enable runtime loading of tsconfig.json
bun build --compile --compile-autoload-tsconfig ./app.ts --outfile myapp

# Enable runtime loading of package.json
bun build --compile --compile-autoload-package-json ./app.ts --outfile myapp

# Enable both
bun build --compile --compile-autoload-tsconfig --compile-autoload-package-json ./app.ts --outfile myapp

Disabling config loading at runtime#

To disable .env or bunfig.toml loading for deterministic execution:

terminal

# Disable .env loading
bun build --compile --no-compile-autoload-dotenv ./app.ts --outfile myapp

# Disable bunfig.toml loading
bun build --compile --no-compile-autoload-bunfig ./app.ts --outfile myapp

# Disable all config loading
bun build --compile --no-compile-autoload-dotenv --no-compile-autoload-bunfig ./app.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./app.ts"],
  compile: {
    // tsconfig.json and package.json are disabled by default
    autoloadTsconfig: true, // Enable tsconfig.json loading
    autoloadPackageJson: true, // Enable package.json loading

    // .env and bunfig.toml are enabled by default
    autoloadDotenv: false, // Disable .env loading
    autoloadBunfig: false, // Disable bunfig.toml loading
    outfile: "./myapp",
  },
});

Act as the Bun CLI#

New in Bun v1.2.16

Set the BUN_BE_BUN=1 environment variable to run a standalone executable as if it were the bun CLI itself. The executable ignores its bundled entrypoint and exposes the full bun CLI instead.

For example, consider an executable compiled from this script:

terminal

echo "console.log(\"you shouldn't see this\");" > such-bun.js
bun build --compile ./such-bun.js

[3ms] bundle 1 modules
[89ms] compile such-bun

Normally, running ./such-bun with arguments executes the script.

terminal

# Executable runs its own entrypoint by default
./such-bun install

you shouldn't see this

However, with the BUN_BE_BUN=1 environment variable, the executable acts like the bun binary:

terminal

# With the env var, the executable acts like the `bun` CLI
BUN_BE_BUN=1 ./such-bun install

bun install v1.2.16-canary.1 (1d1db811)
Checked 63 installs across 64 packages (no changes) [5.00ms]

CLI tools built on top of Bun can use this to install packages, bundle dependencies, or run other files without downloading a separate binary or installing Bun.

Full-stack executables#

New in Bun v1.2.17

The --compile flag can create a standalone executable that contains both server and client code, which suits full-stack applications. When you import an HTML file in your server code, Bun bundles the frontend assets (JavaScript, CSS, and so on) and embeds them into the executable.

import { serve } from "bun";
import index from "./index.html";

const server = serve({
  routes: {
    "/": index,
    "/api/hello": { GET: () => Response.json({ message: "Hello from API" }) },
  },
});

console.log(`Server running at http://localhost:${server.port}`);

<!DOCTYPE html>
<html>
  <head>
    <title>My App</title>
    <link rel="stylesheet" href="./styles.css" />
  </head>
  <body>
    <h1>Hello World</h1>
    <script src="./app.ts"></script>
  </body>
</html>

console.log("Hello from the client!");

body {
  background-color: #f0f0f0;
}

To build this into a single executable:

terminal

bun build --compile ./server.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./server.ts"],
  compile: {
    outfile: "./myapp",
  },
});

This creates a self-contained binary that includes:

Your server code
The Bun runtime
All frontend assets (HTML, CSS, JavaScript)
Any npm packages used by your server

The result is a single file you can deploy anywhere without installing Node.js, Bun, or any dependencies:

terminal

./myapp

Bun serves the frontend assets with the correct MIME types and cache headers. Bun replaces the HTML import with a manifest object that Bun.serve uses to serve the pre-bundled assets.

For more on building full-stack applications, see the full-stack guide.

Worker#

To use workers in a standalone executable, add the worker's entrypoint to the build:

terminal

bun build --compile ./index.ts ./my-worker.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./index.ts", "./my-worker.ts"],
  compile: {
    outfile: "./myapp",
  },
});

Then, reference the worker in your code:

index.ts

console.log("Hello from Bun!");

// Any of these will work:
new Worker("./my-worker.ts");
new Worker(new URL("./my-worker.ts", import.meta.url));
new Worker(new URL("./my-worker.ts", import.meta.url).href);

When you add multiple entrypoints to a standalone executable, Bun bundles each one separately into the executable.

We may eventually detect statically-known paths in new Worker(path) and bundle them automatically. For now, you need to list the worker file as an entrypoint, as in the earlier example.

If you use a relative path to a file not included in the standalone executable, Bun loads that path from disk relative to the process's current working directory, and errors if it doesn't exist.

SQLite#

You can use bun:sqlite imports with bun build --compile.

By default, Bun resolves the database relative to the current working directory of the process.

index.ts

import db from "./my.db" with { type: "sqlite" };

console.log(db.query("select * from users LIMIT 1").get());

That means if the executable is at /usr/bin/hello and the user's terminal is in /home/me/Desktop, Bun looks for /home/me/Desktop/my.db.

terminal

cd /home/me/Desktop
./hello

Embed assets & files#

Standalone executables can embed files directly into the binary, so a single executable can ship images, JSON configs, templates, or any other assets your application needs.

How it works#

Use the with { type: "file" } import attribute to embed a file:

index.ts

import icon from "./icon.png" with { type: "file" };

console.log(icon);
// During development: "./icon.png"
// After compilation: "/$bunfs/root/icon-a1b2c3d4.png" (internal path)

The import returns a path string that points to the embedded file. At build time, Bun:

Reads the file contents
Embeds the data into the executable
Replaces the import with an internal path (prefixed with /$bunfs/)

You can then read this embedded file using Bun.file() or Node.js fs APIs.

Reading embedded files with Bun.file()#

Bun.file() is the recommended way to read embedded files:

index.ts

import icon from "./icon.png" with { type: "file" };
import { file } from "bun";

// Get file contents as different types
const bytes = await file(icon).arrayBuffer(); // ArrayBuffer
const text = await file(icon).text(); // string (for text files)
const blob = file(icon); // Blob

// Stream the file in a response
export default {
  fetch(req) {
    return new Response(file(icon), {
      headers: { "Content-Type": "image/png" },
    });
  },
};

Reading embedded files with Node.js fs#

Embedded files work with the Node.js file system APIs:

index.ts

import icon from "./icon.png" with { type: "file" };
import config from "./config.json" with { type: "file" };
import { readFileSync, promises as fs } from "node:fs";

// Synchronous read
const iconBuffer = readFileSync(icon);

// Async read
const configData = await fs.readFile(config, "utf-8");
const parsed = JSON.parse(configData);

// Check file stats
const stats = await fs.stat(icon);
console.log(`Icon size: ${stats.size} bytes`);

Practical examples#

Embedding a JSON config file#

index.ts

import configPath from "./default-config.json" with { type: "file" };
import { file } from "bun";

// Load the embedded default configuration
const defaultConfig = await file(configPath).json();

// Merge with user config if it exists
const userConfig = await file("./user-config.json")
  .json()
  .catch(() => ({}));
const config = { ...defaultConfig, ...userConfig };

Serving static assets in an HTTP server#

Use static routes in Bun.serve() for efficient static file serving:

server.ts

import favicon from "./favicon.ico" with { type: "file" };
import logo from "./logo.png" with { type: "file" };
import styles from "./styles.css" with { type: "file" };
import { file, serve } from "bun";

serve({
  // Inside the compiled executable, file() on an embedded path returns an
  // in-memory Blob, which routes only accepts wrapped in a Response.
  routes: {
    "/favicon.ico": new Response(file(favicon)),
    "/logo.png": new Response(file(logo)),
    "/styles.css": new Response(file(styles)),
  },
  fetch(req) {
    return new Response("Not found", { status: 404 });
  },
});

Bun automatically handles Content-Type headers and caching for static routes.

Embedding templates#

index.ts

import templatePath from "./email-template.html" with { type: "file" };
import { file } from "bun";

async function sendWelcomeEmail(user: { name: string; email: string }) {
  const template = await file(templatePath).text();
  const html = template.replace("{{name}}", user.name).replace("{{email}}", user.email);

  // Send email with the rendered template...
}

Embedding binary files#

index.ts

import wasmPath from "./processor.wasm" with { type: "file" };
import fontPath from "./font.ttf" with { type: "file" };
import { file } from "bun";

// Load a WebAssembly module
const wasmBytes = await file(wasmPath).arrayBuffer();
const wasmModule = await WebAssembly.instantiate(wasmBytes);

// Read binary font data
const fontData = await file(fontPath).bytes();

Embed SQLite databases#

To embed a SQLite database into the compiled executable, set type: "sqlite" in the import attribute and the embed attribute to "true".

The database file must already exist on disk. Then, import it in your code:

index.ts

import myEmbeddedDb from "./my.db" with { type: "sqlite", embed: "true" };

console.log(myEmbeddedDb.query("select * from users LIMIT 1").get());

Finally, compile it into a standalone executable:

terminal

bun build --compile ./index.ts --outfile mycli

The database file must exist on disk when you run bun build --compile. The embed: "true" attribute tells the bundler to include the database contents inside the compiled executable. When running normally with bun run, Bun loads the database file from disk like a regular SQLite import.

In the compiled executable, the embedded database is read-write. Because the database is stored in memory, all changes are lost when the executable exits.

Embed N-API Addons#

You can embed .node files into executables.

index.ts

const addon = require("./addon.node");

console.log(addon.hello());

If you're using @mapbox/node-pre-gyp or similar tools, require the .node file directly, or it won't bundle correctly.

Embed directories#

Use --asset (or compile.assets in the JavaScript API) to embed a file or directory tree into the executable under its original relative path. The embedded files live under import.meta.dir at runtime and are reachable via node:fs (existsSync, statSync, readdirSync, readFileSync) and Bun.file().

terminal

bun build --compile ./index.ts --asset ./public --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./index.ts"],
  compile: {
    outfile: "./myapp",
    assets: ["./public"],
  },
});

index.ts

import fs from "node:fs";
import path from "node:path";

const publicDir = path.join(import.meta.dir, "public");

for (const entry of fs.readdirSync(publicDir, { withFileTypes: true })) {
  console.log(entry.name, entry.isDirectory() ? "(dir)" : fs.statSync(path.join(publicDir, entry.name)).size);
}

const html = await Bun.file(path.join(publicDir, "index.html")).text();

Pass --asset multiple times to embed several directories (for example --asset ./client --asset ./prerendered for a SvelteKit build). Bun embeds only regular files; it skips symlinks and empty subdirectories inside the tree.

You can also embed individual files via the with { type: "file" } import attribute or, for files that use the file loader (images, fonts, and so on) as well as .wasm and .node files, by adding them as extra entry points. Bun renames imported assets according to --asset-naming (default [name]-[hash].[ext]):

import icon from "./public/assets/icon.png" with { type: "file" };

Detecting standalone mode at runtime#

Use Bun.isStandaloneExecutable to check whether the current process is running from a compiled binary:

index.ts

if (Bun.isStandaloneExecutable) {
  // Running from `bun build --compile` output
} else {
  // Running via `bun <file>` or as a library
}

Unlike Bun.embeddedFiles.length > 0, this check does not allocate Blob objects for each embedded file, so it is safe to call at startup in binaries that embed large assets.

Listing embedded files#

Bun.embeddedFiles exposes all embedded files as Blob objects:

index.ts

import "./icon.png" with { type: "file" };
import "./data.json" with { type: "file" };
import "./template.html" with { type: "file" };
import { embeddedFiles } from "bun";

// List all embedded files
for (const blob of embeddedFiles) {
  console.log(`${blob.name} - ${blob.size} bytes`);
}
// Output:
//   icon-a1b2c3d4.png - 4096 bytes
//   data-e5f6g7h8.json - 256 bytes
//   template-i9j0k1l2.html - 1024 bytes

Each item in Bun.embeddedFiles is a Blob with a name property:

embeddedFiles: ReadonlyArray<Blob>;

Use it to serve every embedded asset through static routes:

server.ts

import "./public/favicon.ico" with { type: "file" };
import "./public/logo.png" with { type: "file" };
import "./public/styles.css" with { type: "file" };
import { embeddedFiles, serve } from "bun";

// Build static routes from all embedded files
const staticRoutes: Record<string, Response> = {};
for (const blob of embeddedFiles) {
  // Remove hash from filename: "icon-a1b2c3d4.png" -> "icon.png"
  const name = blob.name.replace(/-[a-z0-9]+\./, ".");
  // embeddedFiles are plain Blobs, which routes does not accept directly
  staticRoutes[`/${name}`] = new Response(blob);
}

serve({
  routes: staticRoutes,
  fetch(req) {
    return new Response("Not found", { status: 404 });
  },
});

Bun.embeddedFiles excludes bundled source code (.ts, .js, etc.) to help protect your application's source.

Content hash#

By default, Bun appends a content hash to the name of each embedded file, which helps with cache invalidation when you serve the files from a URL or CDN. To keep the original name instead, configure asset naming:

terminal

bun build --compile --asset-naming="[name].[ext]" ./index.ts

build.ts

await Bun.build({
  entrypoints: ["./index.ts"],
  compile: {
    outfile: "./myapp",
  },
  naming: {
    asset: "[name].[ext]",
  },
});

Minification#

To trim down the size of the executable, enable minification:

terminal

bun build --compile --minify ./index.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./index.ts"],
  compile: {
    outfile: "./myapp",
  },
  minify: true, // Enable all minification
});

// Or granular control:
await Bun.build({
  entrypoints: ["./index.ts"],
  compile: {
    outfile: "./myapp",
  },
  minify: {
    whitespace: true,
    syntax: true,
    identifiers: true,
  },
});

This uses Bun's minifier to reduce the code size. Overall though, Bun's binary is still way too big and we need to make it smaller.

Windows-specific flags#

When compiling a standalone executable on Windows, platform-specific options customize metadata on the generated .exe file:

terminal

# Custom icon
bun build --compile --windows-icon=path/to/icon.ico ./app.ts --outfile myapp

# Hide console window (for GUI apps)
bun build --compile --windows-hide-console ./app.ts --outfile myapp

build.ts

await Bun.build({
  entrypoints: ["./app.ts"],
  compile: {
    outfile: "./myapp",
    windows: {
      icon: "./path/to/icon.ico",
      hideConsole: true,
      // Additional Windows metadata:
      title: "My Application",
      publisher: "My Company",
      version: "1.0.0",
      description: "A standalone Windows application",
      copyright: "Copyright 2024",
    },
  },
});

Available Windows options:

icon - Path to .ico file for the executable icon
hideConsole - Disable the background terminal (for GUI apps)
title - Application title in file properties
publisher - Publisher name in file properties
version - Version string in file properties
description - Description in file properties
copyright - Copyright notice in file properties

Except for hideConsole, you can't use these flags when cross-compiling because they depend on Windows APIs.

Code signing on macOS#

To codesign a standalone executable on macOS (which fixes Gatekeeper warnings), use the codesign command.

terminal

codesign --deep --force -vvvv --sign "XXXXXXXXXX" ./myapp

We recommend including an entitlements.plist file with JIT permissions.

entitlements.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>com.apple.security.cs.allow-jit</key>
    <true/>
    <key>com.apple.security.cs.allow-unsigned-executable-memory</key>
    <true/>
    <key>com.apple.security.cs.disable-executable-page-protection</key>
    <true/>
    <key>com.apple.security.cs.allow-dyld-environment-variables</key>
    <true/>
    <key>com.apple.security.cs.disable-library-validation</key>
    <true/>
</dict>
</plist>

To codesign with JIT support, pass the --entitlements flag to codesign.

terminal

codesign --deep --force -vvvv --sign "XXXXXXXXXX" --entitlements entitlements.plist ./myapp

After codesigning, verify the executable:

terminal

codesign -vvv --verify ./myapp
./myapp: valid on disk
./myapp: satisfies its Designated Requirement

Codesign support requires Bun v1.2.4 or newer.

Code splitting#

Standalone executables support code splitting. Use --compile with --splitting to create an executable that loads code-split chunks at runtime.

terminal

bun build --compile --splitting ./src/entry.ts --outfile ./build/entry

build.ts

await Bun.build({
  entrypoints: ["./src/entry.ts"],
  compile: true,
  splitting: true,
  outdir: "./build",
});

console.log("Entrypoint loaded");
const lazy = await import("./lazy.ts");
lazy.hello();

export function hello() {
  console.log("Lazy module loaded");
}

terminal

./build/entry

Entrypoint loaded
Lazy module loaded

Using plugins#

Plugins work with standalone executables; use them to transform files during the build:

build.ts

import type { BunPlugin } from "bun";

const envPlugin: BunPlugin = {
  name: "env-loader",
  setup(build) {
    build.onLoad({ filter: /\.env\.json$/ }, async args => {
      // Transform .env.json files into validated config objects
      const env = await Bun.file(args.path).json();

      return {
        contents: `export default ${JSON.stringify(env)};`,
        loader: "js",
      };
    });
  },
};

await Bun.build({
  entrypoints: ["./cli.ts"],
  compile: {
    outfile: "./mycli",
  },
  plugins: [envPlugin],
});

Example use case - embedding environment config at build time:

cli.ts

import config from "./config.env.json";

console.log(`Running in ${config.environment} mode`);
console.log(`API endpoint: ${config.apiUrl}`);

Plugins can perform any transformation: compile YAML/TOML configs, inline SQL queries, generate type-safe API clients, or preprocess templates. See the plugin documentation.

Unsupported CLI arguments#

The --compile flag does not support the following flags:

--outdir — use outfile instead.
--public-path
--target=node
--target=browser (without HTML entrypoints — see Standalone HTML for --compile --target=browser with .html files)
--no-bundle - Bun always bundles everything into the executable.

API reference#

The compile option in Bun.build() accepts three forms:

types

interface BuildConfig {
  entrypoints: string[];
  compile: boolean | Bun.Build.CompileTarget | CompileBuildOptions;
  // ... other BuildConfig options (minify, sourcemap, define, plugins, etc.)
}

interface CompileBuildOptions {
  target?: Bun.Build.CompileTarget; // Cross-compilation target
  outfile?: string; // Output executable path
  assets?: string[]; // Files/directories to embed under import.meta.dir
  execArgv?: string[]; // Runtime arguments (process.execArgv)
  executablePath?: string; // Bun executable to use instead of downloading one for target
  autoloadTsconfig?: boolean; // Load tsconfig.json (default: false)
  autoloadPackageJson?: boolean; // Load package.json (default: false)
  autoloadDotenv?: boolean; // Load .env files (default: true)
  autoloadBunfig?: boolean; // Load bunfig.toml (default: true)
  windows?: {
    icon?: string; // Path to .ico file
    hideConsole?: boolean; // Hide console window
    title?: string; // Application title
    publisher?: string; // Publisher name
    version?: string; // Version string
    description?: string; // Description
    copyright?: string; // Copyright notice
  };
}

Usage forms:

// Simple boolean - compile for current platform (uses entrypoint name as output)
compile: true

// Target string - cross-compile (uses entrypoint name as output)
compile: "bun-linux-x64"

// Full options object - specify outfile and other options
compile: {
  target: "bun-linux-x64",
  outfile: "./myapp",
}

Supported targets#

Bun.Build.CompileTarget

type CompileTarget =
  | "bun-darwin-x64"
  | "bun-darwin-arm64"
  | "bun-linux-x64"
  | "bun-linux-arm64"
  | "bun-linux-x64-musl"
  | "bun-linux-x64-baseline-musl"
  | "bun-linux-arm64-musl"
  | "bun-windows-x64"
  | "bun-windows-arm64";
// The "-baseline" and "-modern" suffixes are accepted for backward
// compatibility and resolve to the same x64 binary.

Complete example#

build.ts

import type { BunPlugin } from "bun";

const myPlugin: BunPlugin = {
  name: "my-plugin",
  setup(build) {
    // Plugin implementation
  },
};

const result = await Bun.build({
  entrypoints: ["./src/cli.ts"],
  compile: {
    target: "bun-linux-x64",
    outfile: "./dist/mycli",
    execArgv: ["--smol"],
    autoloadDotenv: false,
    autoloadBunfig: false,
  },
  minify: true,
  sourcemap: "linked",
  bytecode: true,
  define: {
    "process.env.NODE_ENV": JSON.stringify("production"),
    VERSION: JSON.stringify("1.0.0"),
  },
  plugins: [myPlugin],
});

if (result.success) {
  console.log("Build successful:", result.outputs[0].path);
}

Cross-compile to other platforms#

Supported targets#

Build-time constants#

Deploying to production#

Bytecode compilation#

What do these flags do?#

Embedding runtime arguments#

Runtime arguments via BUN_OPTIONS#

Automatic config loading#

Enabling config loading at runtime#

Disabling config loading at runtime#

Act as the Bun CLI#

Full-stack executables#

Worker#

SQLite#

Embed assets & files#

How it works#

Reading embedded files with Bun.file()#

Reading embedded files with Node.js fs#

Practical examples#

Embedding a JSON config file#

Serving static assets in an HTTP server#

Embedding templates#

Embedding binary files#

Embed SQLite databases#

Embed N-API Addons#

Embed directories#

Detecting standalone mode at runtime#

Listing embedded files#

Content hash#

Minification#

Windows-specific flags#

Code signing on macOS#

Code splitting#

Using plugins#

Unsupported CLI arguments#

API reference#

Supported targets#

Complete example#

Runtime arguments via `BUN_OPTIONS`#