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Unbuild

๐Ÿ“ฆ A unified JavaScript build system

From unjsยทUpdated May 25, 2026ยทView on GitHubยท

> [!NOTE] > We are experimenting with [obuild](https://github.com/unjs/obuild) as the next next-gen successor based on [rolldown](https://github.com/rolldown/rolldown). > > If you mainly need faster build speeds and don't mind trying beta software, give it a try! The project is written primarily in TypeScript, distributed under the MIT License license, first published in 2021. It has gained significant community traction with 2,734 stars and 107 forks on GitHub. Key topics include: universal-javascript.

Latest release: v3.6.1
August 15, 2025View Changelog โ†’

unbuild

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A unified JavaScript build system

[!NOTE]
We are experimenting with obuild as the next next-gen successor based on rolldown.

If you mainly need faster build speeds and don't mind trying beta software, give it a try!

๐Ÿ“ฆ Optimized bundler

Robust rollup based bundler that supports TypeScript and generates CommonJS and module formats + type declarations.

๐Ÿช„ Automated config

Automagically infer build config and entries from package.json.

๐Ÿ“ Bundleless build

Integration with mkdist for generating bundleless dists with file-to-file transpilation.

โœจ Passive watcher

Stub dist once using unbuild --stub (powered by jiti) and you can try and link your project without needing to watch and rebuild during development.

โœ Untype Generator

Integration with untyped.

โœ”๏ธ Secure builds

Automatically check for various build issues such as potential missing and unused dependencies and fail CI.

CLI output also includes output size and exports for quick inspection.

Usage

Create src/index.ts:

js
export const log = (...args) => { console.log(...args); };

Update package.json:

json
{ "type": "module", "scripts": { "build": "unbuild", "prepack": "unbuild" }, "exports": { ".": { "import": "./dist/index.mjs", "require": "./dist/index.cjs" } }, "main": "./dist/index.cjs", "types": "./dist/index.d.ts", "files": ["dist"] }

Note
You can find a more complete example in unjs/template for project setup.

Build with unbuild:

sh
npx unbuild

Configuration is automatically inferred from fields in package.json mapped to src/ directory. For more control, continue with next section.

Configuration

Create build.config.ts:

js
export default { entries: ["./src/index"], };

You can either use unbuild key in package.json or build.config.{js,cjs,mjs,ts,mts,cts,json} to specify configuration.

See options here.

Example:

js
import { defineBuildConfig } from "unbuild"; export default defineBuildConfig({ // If entries is not provided, will be automatically inferred from package.json entries: [ // default "./src/index", // mkdist builder transpiles file-to-file keeping original sources structure { builder: "mkdist", input: "./src/package/components/", outDir: "./build/components", }, ], // Change outDir, default is 'dist' outDir: "build", // Generates .d.ts declaration file declaration: true, });

Or with multiple builds you can declare an array of configs:

js
import { defineBuildConfig } from "unbuild"; export default defineBuildConfig([ { // If entries is not provided, will be automatically inferred from package.json entries: [ // default "./src/index", // mkdist builder transpiles file-to-file keeping original sources structure { builder: "mkdist", input: "./src/package/components/", outDir: "./build/components", }, ], // Change outDir, default is 'dist' outDir: "build", /** * * `compatible` means "src/index.ts" will generate "dist/index.d.mts", "dist/index.d.cts" and "dist/index.d.ts". * * `node16` means "src/index.ts" will generate "dist/index.d.mts" and "dist/index.d.cts". * * `true` is equivalent to `compatible`. * * `false` will disable declaration generation. * * `undefined` will auto detect based on "package.json". If "package.json" has "types" field, it will be `"compatible"`, otherwise `false`. */ declaration: "compatible", }, { name: "minified", entries: ["./src/index"], outDir: "build/min", rollup: { esbuild: { minify: true, }, }, }, ]);

Recipes

Decorators support

In build.config.ts

ts
import { defineBuildConfig } from "unbuild"; export default defineBuildConfig({ rollup: { esbuild: { tsconfigRaw: { compilerOptions: { experimentalDecorators: true, }, }, }, }, });

Generate sourcemaps

ts
import { defineBuildConfig } from "unbuild"; export default defineBuildConfig({ sourcemap: true, });

๐Ÿ’ป Development

  • Clone this repository
  • Enable Corepack using corepack enable (use npm i -g corepack for Node.js < 16.10)
  • Install dependencies using pnpm install
  • Run interactive tests using pnpm dev

License

MIT

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Contributors

Showing top 12 contributors by commit count.

View all contributors on GitHub โ†’

This article is auto-generated from unjs/unbuild via the GitHub API.Last fetched: 6/1/2026