Next.js and Turbopack

Next.js 16+ uses Turbopack by default for local development: an incremental bundler written in Rust that significantly speeds up dev startup and hot updates.

When to Use

• Turbopack (default dev): Use for day-to-day development. Faster cold start and HMR, especially in large apps.
• Webpack (legacy dev): Use only if you hit a Turbopack bug or rely on a webpack-only plugin in dev. Disable with --webpack (or --no-turbopack depending on your Next.js version; check the docs for your release).
• Production: Production build behavior (next build) may use Turbopack or webpack depending on Next.js version; check the official Next.js docs for your version.

Use when: developing or debugging Next.js 16+ apps, diagnosing slow dev startup or HMR, or optimizing production bundles.

How It Works

• Turbopack: Incremental bundler for Next.js dev. Uses file-system caching so restarts are much faster (e.g. 5–14x on large projects).
• Default in dev: From Next.js 16, next dev runs with Turbopack unless disabled.
• File-system caching: Restarts reuse previous work; cache is typically under .next; no extra config needed for basic use.
• Bundle Analyzer (Next.js 16.1+): Experimental Bundle Analyzer to inspect output and find heavy dependencies; enable via config or experimental flag (see Next.js docs for your version).