Guide

Whether you are publishing your first npm package or maintaining a monorepo with dozens of libraries, these guides walk you through every step — from installation to production builds.

Recommended reading order

If you are new to Packem, start at the top and work your way down. Each guide builds on the previous one.

1. Introduction — What Packem is, how it works, and when to use it.
2. Getting Started — Install Packem and create your first bundle in under five minutes.
3. Configuration — Customize entry points, output formats, and build behavior.
4. Transformers — Pick the right compiler (esbuild, swc, OXC, sucrase, or TypeScript).
5. CSS Processing — Add support for CSS, Sass, Less, Stylus, PostCSS, and CSS Modules.
6. Debug and Profiling — Diagnose build issues and measure performance.

Working with Packem

Task-focused guides for everyday development:

• package.json Setup — Drive entries, formats, and declarations from your package.json.
• TypeScript — Declaration files, isolated declarations, and type checking.
• React — Build React component libraries, including Server Components.
• Multi-Runtime Builds — Target Node.js, browser, edge, and react-server from one build.
• Plugins — Extend the build with Rollup plugins.
• Optimization — Minification, tree shaking, and bundle size.
• Watch Mode — Rebuild automatically during development.
• CLI — Every command and flag the packem CLI offers.

Migrating to Packem

Coming from another bundler? Start here:

• From tsup — Automated migration via packem migrate.
• From unbuild — Automated migration via packem migrate.
• From Rollup — Map your Rollup config to Packem.
• From webpack — Move a webpack library build to Packem.

Troubleshooting

When something goes wrong:

• Common Issues — Frequent problems and their fixes.
• TypeScript — Declaration and type-checking errors.
• CSS — Styling and preprocessor problems.
• Build Errors — Diagnose and resolve build failures.

Already familiar with Packem?

Jump straight to the reference material:

• Configuration Options — Every option explained with examples.
• API Reference — Programmatic usage, hooks, and plugin development.
• Examples — Copy-and-paste starter projects for common setups.