next.js/docs/02-app/02-api-reference/08-next-cli.mdx

---
title: Next.js CLI
description: Learn how the Next.js CLI allows you to develop, build, and start your application, and more.
---

{/* The content of this doc is shared between the app and pages router. You can use the `<PagesOnly>Content</PagesOnly>` component to add content that is specific to the Pages Router. Any shared content should not be wrapped in a component. */}

The Next.js CLI allows you to develop, build, start your application, and more.

To get a list of the available CLI commands, run the following command inside your project directory:

```bash filename="Terminal"
next -h
```

The output should look like this:

```bash filename="Terminal"
Usage next [options] [command]

The Next.js CLI allows you to develop, build, start your application, and more.

Options:
  -v, --version                Outputs the Next.js version.
  -h, --help                   Displays this message.

Commands:
  build [directory] [options]  Creates an optimized production build of your application.
                               The output displays information about each route.
  dev [directory] [options]    Starts Next.js in development mode with hot-code reloading,
                               error reporting, and more.
  info [options]               Prints relevant details about the current system which can be
                               used to report Next.js bugs.
  lint [directory] [options]   Runs ESLint for all files in the `/src`, `/app`, `/pages`,
                               `/components`, and `/lib` directories. It also provides a
                               guided setup to install any required dependencies if ESLint
                               is not already configured in your application.
  start [directory] [options]  Starts Next.js in production mode. The application should be
                               compiled with `next build` first.
  telemetry [options]          Allows you to enable or disable Next.js' completely
                               anonymous telemetry collection.
```

You can pass any [node arguments](https://nodejs.org/api/cli.html#cli_node_options_options) to `next` commands:

```bash filename="Terminal"
NODE_OPTIONS='--throw-deprecation' next
NODE_OPTIONS='-r esm' next
NODE_OPTIONS='--inspect' next
```

> **Good to know**: Running `next` without a command is the same as running `next dev`

## Development

`next dev` starts the application in development mode with hot-code reloading, error reporting, and more.

To get a list of the available options with `next dev`, run the following command inside your project directory:

```bash filename="Terminal"
next dev -h
```

The output should look like this:

```bash filename="Terminal"
Usage: next dev [directory] [options]

Starts Next.js in development mode with hot-code reloading, error reporting, and more.

Arguments:
  [directory]                              A directory on which to build the application.
                                           If no directory is provided, the current
                                           directory will be used.

Options:
  --turbo                                  Starts development mode using Turbopack (beta).
  -p, --port <port>                        Specify a port number on which to start the
                                           application. (default: 3000, env: PORT)
  -H, --hostname <hostname>                Specify a hostname on which to start the
                                           application (default: 0.0.0.0).
  --experimental-https                     Starts the server with HTTPS and generates a
                                           self-signed certificate.
  --experimental-https-key, <path>         Path to a HTTPS key file.
  --experimental-https-cert, <path>        Path to a HTTPS certificate file.
  --experimental-https-ca, <path>          Path to a HTTPS certificate authority file.
  --experimental-upload-trace, <traceUrl>  Reports a subset of the debugging trace to a
                                           remote HTTP URL. Includes sensitive data.
  -h, --help                               Displays this message.
```

The application will start at `http://localhost:3000` by default. The default port can be changed with `-p`, like so:

```bash filename="Terminal"
next dev -p 4000
```

Or using the `PORT` environment variable:

```bash filename="Terminal"
PORT=4000 next dev
```

> **Good to know**:
>
> - `PORT` cannot be set in `.env` as booting up the HTTP server happens before any other code is initialized.
> - Next.js will automatically retry with another port until a port is available if a port is not specified with the CLI option `--port` or the `PORT` environment variable.

You can also set the hostname to be different from the default of `0.0.0.0`, this can be useful for making the application available for other devices on the network. The default hostname can be changed with `-H`, like so:

```bash filename="Terminal"
next dev -H 192.168.1.2
```

### Turbopack

[Turbopack](/docs/architecture/turbopack) (beta), our new bundler, which is being tested and stabilized in Next.js, helps speed up local iterations while working on your application.

To use Turbopack in development mode, add the `--turbo` option:

```bash filename="Terminal"
next dev --turbo
```

### HTTPS for Local Development

For certain use cases like webhooks or authentication, it may be required to use HTTPS to have a secure environment on `localhost`. Next.js can generate a self-signed certificate with `next dev` as follows:

```bash filename="Terminal"
next dev --experimental-https
```

You can also provide a custom certificate and key with `--experimental-https-key` and `--experimental-https-cert`. Optionally, you can provide a custom CA certificate with `--experimental-https-ca` as well.

```bash filename="Terminal"
next dev --experimental-https --experimental-https-key ./certificates/localhost-key.pem --experimental-https-cert ./certificates/localhost.pem
```

`next dev --experimental-https` is only intended for development and creates a locally-trusted certificate with `mkcert`. In production, use properly issued certificates from trusted authorities. When deploying to Vercel, HTTPS is [automatically configured](https://vercel.com/docs/security/encryption) for your Next.js application.

## Build

`next build` creates an optimized production build of your application. The output displays information about each route:

```bash filename="Terminal"
Route (app)                               Size     First Load JS
┌ ○ /                                     5.3 kB         89.5 kB
├ ○ /_not-found                           885 B          85.1 kB
└ ○ /about                                137 B          84.4 kB
+ First Load JS shared by all             84.2 kB
  ├ chunks/184-d3bb186aac44da98.js        28.9 kB
  ├ chunks/30b509c0-f3503c24f98f3936.js   53.4 kB
  └ other shared chunks (total)


○  (Static)  prerendered as static content
```

- **Size**: The number of assets downloaded when navigating to the page client-side. The size for each route only includes its dependencies.
- **First Load JS**: The number of assets downloaded when visiting the page from the server. The amount of JS shared by all is shown as a separate metric.

Both of these values are [**compressed with gzip**](/docs/app/api-reference/next-config-js/compress). The first load is indicated by green, yellow, or red. Aim for green for performant applications.

To get a list of the available options with `next build`, run the following command inside your project directory:

```bash filename="Terminal"
next build -h
```

The output should look like this:

```bash filename="Terminal"
Usage: next build [directory] [options]

Creates an optimized production build of your application. The output displays information
about each route.

Arguments:
  [directory]                       A directory on which to build the application. If no
                                    provided, the current directory will be
                                    used.

Options:
  -d, --debug                       Enables a more verbose build output.
  --profile                         Enables production profiling for React.
  --no-lint                         Disables linting.
  --no-mangling                     Disables mangling.
  --experimental-app-only           Builds only App Router routes.
  --experimental-build-mode [mode]  Uses an experimental build mode. (choices: "compile"
                                    "generate", default: "default")
  -h, --help                        Displays this message.
```

### Debug

You can enable more verbose build output with the `--debug` flag in `next build`.

```bash filename="Terminal"
next build --debug
```

With this flag enabled additional build output like rewrites, redirects, and headers will be shown.

### Linting

You can disable linting for builds like so:

```bash filename="Terminal"
next build --no-lint
```

### Mangling

You can disable [mangling](https://en.wikipedia.org/wiki/Name_mangling) for builds like so:

```bash filename="Terminal"
next build --no-mangling
```

> **Good to know**: This may affect performance and should only be used for debugging purposes.

### Profiling

You can enable production profiling for React with the `--profile` flag in `next build`.

```bash filename="Terminal"
next build --profile
```

After that, you can use the profiler in the same way as you would in development.

## Production

`next start` starts the application in production mode. The application should be compiled with [`next build`](#build) first.

To get a list of the available options with `next start`, run the follow command inside your project directory:

```bash filename="Terminal"
next start -h
```

The output should look like this:

```bash filename="Terminal"
Usage: next start [directory] [options]

Starts Next.js in production mode. The application should be compiled with `next build`
first.

Arguments:
  [directory]                           A directory on which to start the application.
                                        If not directory is provided, the current
                                        directory will be used.

Options:
  -p, --port <port>                     Specify a port number on which to start the
                                        application. (default: 3000, env: PORT)
  -H, --hostname <hostname>             Specify a hostname on which to start the
                                        application (default: 0.0.0.0).
  --keepAliveTimeout <keepAliveTimeout> Specify the maximum amount of milliseconds to wait
                                        before closing the inactive connections.
  -h, --help                            Displays this message.
```

The application will start at `http://localhost:3000` by default. The default port can be changed with `-p`, like so:

```bash filename="Terminal"
next start -p 4000
```

Or using the `PORT` environment variable:

```bash filename="Terminal"
PORT=4000 next start
```

> **Good to know**:
>
> - `PORT` cannot be set in `.env` as booting up the HTTP server happens before any other code is initialized.
> - `next start` cannot be used with `output: 'standalone'` or `output: 'export'`.

### Keep Alive Timeout

When deploying Next.js behind a downstream proxy (e.g. a load-balancer like AWS ELB/ALB) it's important to configure Next's underlying HTTP server with [keep-alive timeouts](https://nodejs.org/api/http.html#http_server_keepalivetimeout) that are _larger_ than the downstream proxy's timeouts. Otherwise, once a keep-alive timeout is reached for a given TCP connection, Node.js will immediately terminate that connection without notifying the downstream proxy. This results in a proxy error whenever it attempts to reuse a connection that Node.js has already terminated.

To configure the timeout values for the production Next.js server, pass `--keepAliveTimeout` (in milliseconds) to `next start`, like so:

```bash filename="Terminal"
next start --keepAliveTimeout 70000
```

## Info

`next info` prints relevant details about the current system which can be used to report Next.js bugs.
This information includes Operating System platform/arch/version, Binaries (Node.js, npm, Yarn, pnpm) and npm package versions (`next`, `react`, `react-dom`).

To get a list of the available options with `next info`, run the following command inside your project directory:

```bash filename="Terminal"
next info -h
```

The output should look like this:

```bash filename="Terminal"
Usage: next info [options]

Prints relevant details about the current system which can be used to report Next.js bugs.

Options:
  --verbose   Collections additional information for debugging.
  -h, --help  Displays this message.
```

Running `next info` will give you information like this example:

```bash filename="Terminal"

Operating System:
  Platform: linux
  Arch: x64
  Version: #22-Ubuntu SMP Fri Nov 5 13:21:36 UTC 2021
  Available memory (MB): 31795
  Available CPU cores: 16
Binaries:
  Node: 16.13.0
  npm: 8.1.0
  Yarn: 1.22.17
  pnpm: 6.24.2
Relevant Packages:
  next: 14.1.1-canary.61 // Latest available version is detected (14.1.1-canary.61).
  react: 18.2.0
  react-dom: 18.2.0
Next.js Config:
  output: N/A

```

This information should then be pasted into GitHub Issues.

You can also run `next info --verbose` which will print additional information about the system and the installation of packages related to `next`.

## Lint

`next lint` runs ESLint for all files in the `pages/`, `app/`, `components/`, `lib/`, and `src/` directories. It also
provides a guided setup to install any required dependencies if ESLint is not already configured in
your application.

To get a list of the available options with `next lint`, run the following command inside your project directory:

```bash filename="Terminal"
next lint -h
```

The output should look like this:

```bash filename="Terminal"
Usage: next lint [directory] [options]

Runs ESLint for all files in the `/src`, `/app`, `/pages`, `/components`, and `/lib` directories. It also
provides a guided setup to install any required dependencies if ESLint is not already configured in your
application.

Arguments:
  [directory]                                         A base directory on which to lint the application.
                                                      If no directory is provided, the current directory
                                                      will be used.

Options:
  -d, --dir, <dirs...>                                Include directory, or directories, to run ESLint.
  --file, <files...>                                  Include file, or files, to run ESLint.
  --ext, [exts...]                                    Specify JavaScript file extensions. (default:
                                                      [".js", ".mjs", ".cjs", ".jsx", ".ts", ".mts", ".cts", ".tsx"])
  -c, --config, <config>                              Uses this configuration file, overriding all other
                                                      configuration options.
  --resolve-plugins-relative-to, <rprt>               Specify a directory where plugins should be resolved
                                                      from.
  --strict                                            Creates a `.eslintrc.json` file using the Next.js
                                                      strict configuration.
  --rulesdir, <rulesdir...>                           Uses additional rules from this directory(s).
  --fix                                               Automatically fix linting issues.
  --fix-type <fixType>                                Specify the types of fixes to apply (e.g., problem,
                                                      suggestion, layout).
  --ignore-path <path>                                Specify a file to ignore.
  --no-ignore <path>                                  Disables the `--ignore-path` option.
  --quiet                                             Reports errors only.
  --max-warnings [maxWarnings]                        Specify the number of warnings before triggering a
                                                      non-zero exit code. (default: -1)
  -o, --output-file, <outputFile>                     Specify a file to write report to.
  -f, --format, <format>                              Uses a specifc output format.
  --no-inline-config                                  Prevents comments from changing config or rules.
  --report-unused-disable-directives-severity <level> Specify severity level for unused eslint-disable
                                                      directives. (choices: "error", "off", "warn")
  --no-cache                                          Disables caching.
  --cache-location, <cacheLocation>                   Specify a location for cache.
  --cache-strategy, [cacheStrategy]                   Specify a strategy to use for detecting changed files
                                                      in the cache. (default: "metadata")
  --error-on-unmatched-pattern                        Reports errors when any file patterns are unmatched.
  -h, --help                                          Displays this message.
```

If you have other directories that you would like to lint, you can specify them using the `--dir` flag:

```bash filename="Terminal"
next lint --dir utils
```

For more information on the other options, check out our [ESLint](/docs/app/building-your-application/configuring/eslint) configuration documentation.

## Telemetry

Next.js collects **completely anonymous** telemetry data about general usage.
Participation in this anonymous program is optional, and you may opt-out if you'd not like to share any information.

To get a list of the available options with `next telemetry`, run the following command in your project directory:

```bash filename="Terminal"
next telemetry -h
```

The output should look like this:

```bash filename="Terminal"
Usage: next telemetry [options]

Allows you to enable or disable Next.js' completely anonymous telemetry collection.

Options:
  --enable    Eanbles Next.js' telemetry collection.
  --disable   Disables Next.js' telemetry collection.
  -h, --help  Displays this message.

Learn more: https://nextjs.org/telemetry
```

Learn more about [Telemetry](/telemetry/).