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zero config bundler for JavaScript/TypeScript/JSX library


Bunchee can help you to bundle your library into one file with zero configuration. It's built on top of rollup and babel. Let you focus on writing code and can generate multiple types of module (commonjs, esmodule) at the same time.


npm install --save-dev bunchee



Declare your main field and module field in package.json, then call bunchee cli in build scripts. If you're using typescript, types will be generated automatically based on your package.json field typings or types.

  • main + module

You can have Commonjs + ESModules output as the simple config

  "main": "dist/pkg.cjs.js",
  "module": "dist/pkg.esm.js",
  "scripts": {
    "build": "bunchee ./src/index.js"
  "types": "dist/types/index.d.ts"

Leverage exports field to support different conditions would be also ideal. Most of the bundler such as webpack can already handle the package exports well. It's convenient to define multiple conditions in exports.

  "exports": {
    "require": "dist/index.cjs",
    "import": "dist/index.mjs",
    "module": "dist/index.esm.js" // module condition
  "scripts": {
    "build": "bunchee ./src/index.js"


Usage: bunchee [options]

  -v, --version          output the version number
  -w, --watch            watch src files changes
  -m, --minify           compress output. false by default
  -o, --output <file>    specify output filename
  -f, --format <format>  specify bundle type: "esm", "cjs", "umd". "esm" by default
  -e, --external <mod>   specify an external dependency
  -h, --help             output usage information
  --target <target>      build environment, use "node" for nodejs runtime
  --no-sourcemap         disable sourcemap generation, sourcemap generation is enabled by default
  --cwd <cwd>            specify current working directory

  $ bunchee ./src/index.js # if you set main fields in package.json
  $ bunchee ./src/index.ts -o ./dist/bundle.js # specify the dist file path


import { bundle } from 'bunchee'

// options is same to CLI options
await bundle(entryFilePath, options)

Example Scripts

cd <project-root-dir>
bunchee ./src/index.js -f cjs -o ./dist/bundle.js

bunchee ./src/index.js -f esm -o ./dist/bundle.esm.js
# if you don't specify format type, default format is ESModule
# bunchee ./src/index.js -o ./dist/bundle.esm.js

Using Typescript

By default bunchee includes Typescript v3.9.x inside as a dependency. If you want to use your own version, just install typescript as another dev dependency then bunchee will automatically pick it.

yarn add -D bunchee typescript

This library requires at least TypeScript 3.7.