unbuild

unbuild — unified build system for JS/TS libraries with zero config.

Build ToolsSimple

Stack Components

Bundlerunbuild 2.x

Baserollup

Why

Zero-config for libraries, dual CJS/ESM output, TypeScript declarations. Vite 5 builds 10-20x faster than Webpack (esbuild + Rollup core).

Turborepo and Nx cut monorepo CI times by 60-80% via remote caching and task parallelization.

When

Use for building npm libraries. Avoid for application bundling.

How

1. npm install unbuild 2. Create build.config.ts 3. npx unbuild 4. Publish to npm 5. Add environment configuration — cp .env.example .env && edit values 6. Run tests — npm test or pnpm test to verify setup 7. Deploy — git push to trigger CI/CD or manual deploy

Example

export default { entries: ['src/index.ts'], declaration: true, rollup: { emitCJS: true }, };

Common Problems

⚠ESM/CJS dual package — use modern-exports config
⚠Missing deps — check externals
⚠Configuration drift between environments — use infrastructure-as-code (Terraform/Pulumi) to keep dev/staging/prod identical

Best Practices

✓Use stub mode for monorepo dev
✓Enable tree-shaking with sideEffects: false
✓Set up health checks and graceful shutdown — handle SIGTERM to drain in-flight requests before exit

FAQ

What is unbuild and what projects is it for?

unbuild — unified build system for JS/TS libraries with zero config. It pairs layered technologies for end-to-end type safety and out-of-the-box deploys, fitting everything from MVPs to production SaaS.

How do I spin up a working demo with unbuild in 10 minutes?

Two steps: (1) npm install unbuild; (2) Create build.config.ts. Get the local dev server running, then wire one real data source to verify the end-to-end loop.

What is the most common pitfall with unbuild and how do I avoid it?

The most common pitfall is: ESM/CJS dual package — use modern-exports config. Avoid it by adding the matching checklist to your PR template and running type-check + lint + unit tests in CI — three gates before merge.

What are the best practices for unbuild?

Best practices for unbuild include: Use stub mode for monorepo dev; Enable tree-shaking with sideEffects: false; Set up health checks and graceful shutdown — handle SIGTERM to drain in-flight requests before exit. The first one — "Use stub mode for monorepo dev" — should be set up at project init to avoid costly rework later.

When should I NOT choose unbuild?

Pick something else in three cases: (1) the team has zero experience with the core framework and the deadline is tight (learning-curve risk); (2) it's a pure content/marketing site (Astro is lighter); (3) you need very high throughput (>10k RPS) or strict-consistency microservices (Go/Rust). unbuild shines for mid-to-high complexity full-stack and API work — don't over-engineer simple static pages with it.