Turbopack

Turbopack is an incremental bundler for JavaScript and TypeScript applications, written in Rust and developed by Vercel. The project is led by Tobias Koppers, the original creator of Webpack, who joined Vercel to build Turbopack as the spiritual successor to Webpack with dramatically faster performance through native Rust execution. Turbopack is integrated directly into Next.js as the default development bundler, replacing Webpack for local development server startup, hot module replacement, and incremental builds. The core architecture uses a unified dependency graph that represents all build environments including client, server, and edge runtimes in a single data structure, eliminating redundant module resolution and parsing across environments. Turbopack implements incremental computation at the function level, caching individual transformation results and reusing them across builds and file changes, with parallel scheduling that distributes work across available CPU cores. A key optimization called lazy bundling means the bundler only processes the modules that the browser actually requests from the dev server, rather than pre-bundling the entire application graph on startup. Turbopack supports both the Pages Router and the App Router in Next.js, and handles CSS, CSS Modules, PostCSS, Tailwind CSS, TypeScript stripping, React Fast Refresh, and image optimization natively without separate plugin configuration. Pre-built native binaries are distributed for macOS, Windows, and Linux in both x64 and ARM64 variants, with a WebAssembly fallback for platforms without native binaries. Turbopack is bundled with Next.js and does not require separate installation.