Turbopack Turbopack is an incremental bundler optimized for JavaScript and TypeScript, written in Rust, and built into Next.js. You can use Turbopack with both the Pages and App Router for a much faster local development experience. Why Turbopack? We built Turbopack to push the performance of Next.js, including: Unified Graph: Next.js supports multiple output environments (e.g., client and server)