Bun Single-file executable

Single-file executable

Generate standalone executables from TypeScript or JavaScript files with Bun

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

console.log("Hello world!");

This bundles cli.ts into an executable that can be executed directly:

./mycli

Hello world!

All imported files and packages are bundled 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

The --target flag lets you 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):

# To support CPUs from before 2013, use the baseline version (nehalem)
bun build --compile --target=bun-linux-x64-baseline ./index.ts --outfile myapp

# To explicitly only support CPUs from 2013 and later, use the modern version (haswell)
# modern is faster, but baseline is more compatible.
bun build --compile --target=bun-linux-x64-modern ./index.ts --outfile myapp
```

// Baseline (pre-2013 CPUs)
await Bun.build({
  entrypoints: ["./index.ts"],
  compile: {
    target: "bun-linux-x64-baseline",
    outfile: "./myapp",
  },
});

// Modern (2013+ CPUs, faster)
await Bun.build({
  entrypoints: ["./index.ts"],
  compile: {
    target: "bun-linux-x64-modern",
    outfile: "./myapp",
  },
});
```

To build for Linux ARM64 (e.g. Graviton or Raspberry Pi):

To build for Windows x64:

# To support CPUs from before 2013, use the baseline version (nehalem)
bun build --compile --target=bun-windows-x64-baseline ./path/to/my/app.ts --outfile myapp

# To explicitly only support CPUs from 2013 and later, use the modern version (haswell)
bun build --compile --target=bun-windows-x64-modern ./path/to/my/app.ts --outfile myapp

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

// Baseline or modern variants
await Bun.build({
  entrypoints: ["./path/to/my/app.ts"],
  compile: {
    target: "bun-windows-x64-baseline",
    outfile: "./myapp",
  },
});
```

To build for macOS arm64:

To build for macOS x64:

Supported targets

The order of the --target flag does not matter, as long as they're delimited by a -.

Build-time constants

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

These constants are embedded directly into your compiled binary at build time, providing zero runtime overhead and enabling dead code elimination optimizations.

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. It costs time and memory to read files from disk, resolve file paths, parse, transpile, and print source code.

With compiled executables, you can move that cost from runtime to build-time.

When deploying to production, we recommend the following:

Bytecode compilation

To improve startup time, enable bytecode compilation:

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. It 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 optimizes the size of the transpiled output code. If you have 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 will automatically decompress & resolve the sourcemap when an error occurs.

The --bytecode argument enables bytecode compilation. Every time you run JavaScript code in Bun, JavaScriptCore (the engine) will compile your source code into bytecode. We can move this parsing work from runtime to bundle time, saving you startup time.

Embedding runtime arguments

--compile-exec-argv="args" - Embed runtime arguments that are available via process.execArgv:

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

Runtime arguments via BUN_OPTIONS

The BUN_OPTIONS environment variable is applied to standalone executables, allowing you to pass runtime flags without recompiling:

# 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

This is useful for debugging or profiling production executables without rebuilding them.

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

Enabling config loading at runtime

If your executable needs to read tsconfig.json or package.json at runtime, you can opt in with the new CLI flags:

# 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:

# 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
```

    // .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

You can run a standalone executable as if it were the bun CLI itself by setting the BUN_BE_BUN=1 environment variable. When this variable is set, the executable will ignore its bundled entrypoint and instead expose all the features of Bun's CLI.

For example, consider an executable compiled from a simple script:

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 would execute the script.

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

you shouldn't see this

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

# 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]

This is useful for building CLI tools on top of Bun that may need to install packages, bundle dependencies, run different or local files and more without needing to download a separate binary or install bun.

Full-stack executables

New in Bun v1.2.17

Bun's --compile flag can create standalone executables that contain both server and client code, making it ideal for full-stack applications. When you import an HTML file in your server code, Bun automatically bundles all frontend assets (JavaScript, CSS, etc.) and embeds them into the executable. When Bun sees the HTML import on the server, it kicks off a frontend build process to bundle JavaScript, CSS, and other assets.

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

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

```html index.html icon="file-code" theme={"theme":{"light":"github-light","dark":"dracula"}}
<!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:

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 that can be deployed anywhere without needing Node.js, Bun, or any dependencies installed. Just run:

./myapp

Bun automatically handles serving the frontend assets with proper MIME types and cache headers. The HTML import is replaced with a manifest object that Bun.serve uses to efficiently serve pre-bundled assets.

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

Worker

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

Then, reference the worker in your code:

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, they will be bundled separately into the executable.

In the future, we may automatically detect usages of statically-known paths in new Worker(path) and then bundle those into the executable, but for now, you'll need to add it to the shell command manually like the above example.

If you use a relative path to a file not included in the standalone executable, it will attempt to load that path from disk relative to the current working directory of the process (and then error if it doesn't exist).

SQLite

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

By default, the database is resolved relative to the current working directory of the process.

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

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

That means if the executable is located at /usr/bin/hello, the user's terminal is located at /home/me/Desktop, it will look for /home/me/Desktop/my.db.

cd /home/me/Desktop
./hello

Embed assets & files

Standalone executables support embedding files directly into the binary. This lets you ship a single executable that contains 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:

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

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

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

1. Reads the file contents
2. Embeds the data into the executable
3. 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:

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 seamlessly with Node.js file system APIs:

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

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:

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({
  static: {
    "/favicon.ico": file(favicon),
    "/logo.png": file(logo),
    "/styles.css": file(styles),
  },
  fetch(req) {
    return new Response("Not found", { status: 404 });
  },
});

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

Embedding templates

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

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

If your application wants 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:

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:

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

In the compiled executable, the embedded database is read-write, but all changes are lost when the executable exits (since it's stored in memory).

Embed N-API Addons

You can embed .node files into executables.

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

console.log(addon.hello());

Unfortunately, if you're using @mapbox/node-pre-gyp or other similar tools, you'll need to make sure the .node file is directly required or it won't bundle correctly.

Embed directories

To embed a directory with bun build --compile, include file patterns in your build:

// Expand glob pattern to file list
const glob = new Glob("./public/**/*.png");
const pngFiles = Array.from(glob.scanSync("."));

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

Then, you can reference the files in your code:

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

export default {
  fetch(req) {
    // Embedded files can be streamed from Response objects
    return new Response(file(icon));
  },
};

This is honestly a workaround, and we expect to improve this in the future with a more direct API.

Listing embedded files

Bun.embeddedFiles gives you access to all embedded files as Blob objects:

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>;

This is useful for dynamically serving all embedded assets using static routes:

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, Blob> = {};
for (const blob of embeddedFiles) {
  // Remove hash from filename: "icon-a1b2c3d4.png" -> "icon.png"
  const name = blob.name.replace(/-[a-f0-9]+\./, ".");
  staticRoutes[`/${name}`] = blob;
}

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

Content hash

By default, embedded files have a content hash appended to their name. This is useful for situations where you want to serve the file from a URL or CDN and have fewer cache invalidation issues. But sometimes, this is unexpected and you might want the original name instead:

To disable the content hash, configure asset naming:

Minification

To trim down the size of the executable, enable 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, there are platform-specific options to customize metadata on the generated .exe file:

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

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

These flags currently cannot be used 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.

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

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

<?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/>
    <ke

…(truncated)