Introduction

Bunup is the ⚡️ blazing-fast build tool for TypeScript libraries, designed for flawless developer experience and speed, powered by Bun.

Performance

Bunup delivers instant builds by design. With Bun's native speed and Bunup's own high-performance dts bundler, cold starts and rebuilds are lightning fast, even in monorepos. Say goodbye to slow bundling and say hello to instant packaging. See benchmarks.

Tool	Build Time (s)	Relative Speed
bunup	0.37 s	baseline
tsdown	0.41 s	1.11× slower
rslib	1.41 s	3.81× slower
unbuild	3.19 s	8.62× slower
tsup	3.37 s	9.11× slower

Quick Start

Quickly scaffold a new modern TypeScript or React library with Bunup in just 10 seconds.

bunx bunup@latest --new

See the Scaffold with Bunup page for more details.

Or, initialize bunup in an existing project:

bunx bunup@latest --init

Getting Started

Get started with Bunup in seconds - install, configure, and build your TypeScript projects with minimal setup.

Basic Usage

Create a TypeScript file:

src/index.ts

export function greet(name: string): string {
	return `Hello, ${name}!`;
}

Bundle it with bunup:

bunx bunup src/index.ts

That's it! This creates bundled output in the dist directory with ESM format (the default), plus TypeScript declaration files (.d.ts) since the entry point is a TypeScript file.

Using with package.json

First, install bunup as a dev dependency:

bun add --dev bunup

Add a build script to your package.json:

package.json

{
	"name": "my-package",
	"scripts": {
		"build": "bunup src/index.ts"
	}
}

Then run:

bun run build

Configuration

Create a bunup.config.ts file for more advanced usage like including plugins, hooks, and advanced options that aren't available via CLI.

For example, you can add the exports plugin to automatically sync your package.json exports on each build - no more manual export management!

bunup.config.ts

import { defineConfig } from 'bunup';
import { exports } from 'bunup/plugins';

export default defineConfig({
	entry: ['src/index.ts'],
	plugins: [exports()],
});

You can also export an array of configurations:

bunup.config.ts

export default defineConfig([
	{
		name: 'node',
		entry: ['src/index.ts'],
		format: ['cjs'],
		target: 'node',
	},
	{
		name: 'browser',
		entry: ['src/index.ts'],
		format: ['esm', 'iife'],
		target: 'browser',
		outDir: "dist/browser",
	},
]);

Package.json Configuration

You can also include your bunup configuration directly in your package.json file using the bunup property:

package.json

{
	"name": "my-package",
	"version": "1.0.0",
	"bunup": {
		"entry": ["src/index.ts", "src/cli.ts"],
		"target": "bun",
	}
}

This approach can be useful when you prefer keeping all project configuration in a single file.

JSON Schema

Bunup provides a JSON schema at https://bunup.dev/schema.json for editor autocompletion and validation. You can enable autocomplete for the bunup field in your package.json by configuring VSCode:

.vscode/settings.json

{
  "json.schemas": [
    {
      "fileMatch": ["package.json"],
      "url": "https://bunup.dev/schema.json"
    }
  ]
}

This provides autocompletion, validation, and documentation when editing the bunup configuration in your package.json file.

Custom Configuration Path

If you need to use a configuration file with a non-standard name or location, you can specify its path using the --config CLI option:

bunup --config ./configs/custom.bunup.config.ts

This is particularly useful for projects with multiple build configurations or for separating build configs for different environments.

Watch Mode

Bunup can watch your files for changes and rebuild automatically:

bunup src/index.ts --watch

Or in package.json:

package.json

{
	"name": "my-package",
	"scripts": {
		"build": "bunup src/index.ts",
		"dev": "bunup src/index.ts --watch"
	}
}

Then run:

bun run dev