Running the Next.js Dev Server: `next dev` Options Explained

The next dev options let you tune the development server's port, hostname, bundler, and protocol. next dev starts the server with hot reloading and error reporting, and running the bare next command is an alias for it, so both start the same server.

Start the server with the npm script:

bash

npm run dev

Visit http://localhost:3000. The server watches your files and pushes updates to the browser as you save.

With npm, put -- before any flag so npm forwards it to Next.js. With pnpm, yarn, or bun, pass flags directly.

The table below lists the flags most people need. The full set also includes CPU profiling and trace upload options, which matter only for performance work.

The most useful options are:

During development, Next.js writes build output to .next/dev instead of .next, so you can run the dev server and a production build side by side.

Change the port

The dev server listens on port 3000 by default, and you can override that. To use a different port, pass --port or -p:

bash

npm run dev -- --port 4000

The server now runs at http://localhost:4000. You can also set the PORT environment variable, but not inside .env, because the server starts before .env is loaded.

Choose the bundler

Turbopack is the default bundler in Next.js 16, so you normally pass no flag at all. Use --webpack only when you need Webpack-specific behavior, and --turbopack or --turbo to force the default back on. Most projects never touch this option.

bash

next dev --webpack

Serve over HTTPS

For testing webhooks or authentication, you can serve the app over a local HTTPS connection. Pass --experimental-https and Next.js generates a certificate for you:

bash

next dev --experimental-https

This creates a self-signed certificate and serves https://localhost:3000, which is enough for local testing but not for production.

Run from another directory

Pass a directory argument to start the server for a project in a different folder, which is handy in monorepos where the app lives in a subfolder. If you pass no directory, Next.js uses the current folder.

bash

next dev apps/web

The server starts for that app while your terminal stays wherever it was.

For how the dev server differs from production, read Next.js Development vs Production Mode. To understand the build command's output, read Understanding next build Output.