---
title: next CLI
description: Learn how to run and build your application with the Next.js CLI.
---
{/* The content of this doc is shared between the app and pages router. You can use the `Content` 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.
Basic usage:
```bash filename="Terminal"
npx next [command] [options]
```
## Reference
The following options are available:
| Options | Description |
| ------------------- | ---------------------------------- |
| `-h` or `--help` | Shows all available options |
| `-v` or `--version` | Outputs the Next.js version number |
### Commands
The following commands are available:
| Command | Description |
| ------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------- |
| [`dev`](#next-dev-options) | Starts Next.js in development mode with Hot Module Reloading, error reporting, and more. |
| [`build`](#next-build-options) | Creates an optimized production build of your application. Displaying information about each route. |
| [`start`](#next-start-options) | Starts Next.js in production mode. The application should be compiled with `next build` first. |
| [`info`](#next-info-options) | Prints relevant details about the current system which can be used to report Next.js bugs. |
| [`telemetry`](#next-telemetry-options) | Allows you to enable or disable Next.js' completely anonymous telemetry collection. |
| [`typegen`](#next-typegen-options) | Generates TypeScript definitions for routes, pages, layouts, and route handlers without running a full build. |
| [`upgrade`](#next-upgrade-options) | Upgrades your Next.js application to the latest version. |
| [`experimental-analyze`](#next-experimental-analyze-options) | Analyzes bundle output using Turbopack. Does not produce build artifacts. |
> **Good to know**: Running `next` without a command is an alias for `next dev`.
### `next dev` options
`next dev` starts the application in development mode with Hot Module Reloading (HMR), error reporting, and more. The following options are available when running `next dev`:
| Option | Description |
| ---------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------- |
| `-h, --help` | Show all available options. |
| `[directory]` | A directory in which to build the application. If not provided, current directory is used. |
| `--turbopack` | Force enable [Turbopack](/docs/app/api-reference/turbopack) (enabled by default). Also available as `--turbo`. |
| `--webpack` | Use Webpack instead of the default [Turbopack](/docs/app/api-reference/turbopack) bundler for development. |
| `-p` or `--port ` | Specify a port number on which to start the application. Default: 3000, env: PORT |
| `-H`or `--hostname ` | Specify a hostname on which to start the application. Useful for making the application available for other devices on the network. Default: 0.0.0.0 |
| `--experimental-https` | Starts the server with HTTPS and generates a self-signed certificate. |
| `--experimental-https-key ` | Path to a HTTPS key file. |
| `--experimental-https-cert ` | Path to a HTTPS certificate file. |
| `--experimental-https-ca ` | Path to a HTTPS certificate authority file. |
| `--experimental-upload-trace ` | Reports a subset of the debugging trace to a remote HTTP URL. |
| `--experimental-cpu-prof` | Enables CPU profiling using V8's inspector. Profiles are saved to `.next/cpu-profiles/` on exit. |
### `next build` options
`next build` creates an optimized production build of your application. The output displays information about each route. For example:
```bash filename="Terminal"
Route (app)
┌ ○ /_not-found
└ ƒ /products/[id]
○ (Static) prerendered as static content
ƒ (Dynamic) server-rendered on demand
```
The following options are available for the `next build` command:
| Option | Description |
| ---------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `-h, --help` | Show all available options. |
| `[directory]` | A directory on which to build the application. If not provided, the current directory will be used. |
| `--turbopack` | Force enable [Turbopack](/docs/app/api-reference/turbopack) (enabled by default). Also available as `--turbo`. |
| `--webpack` | Build using Webpack. |
| `-d` or `--debug` | Enables a more verbose build output. With this flag enabled additional build output like rewrites, redirects, and headers will be shown. |
| |
| `--profile` | Enables production [profiling for React](https://react.dev/reference/react/Profiler). |
| `--no-lint` | Disables linting. _Note: linting will be removed from `next build` in Next 16. If you're using Next 15.5+ with a linter other than `eslint`, linting during build will not occur._ |
| `--no-mangling` | Disables [mangling](https://en.wikipedia.org/wiki/Name_mangling). This may affect performance and should only be used for debugging purposes. |
| `--experimental-app-only` | Builds only App Router routes. |
| `--experimental-build-mode [mode]` | Uses an experimental build mode. (choices: "compile", "generate", default: "default") |
| `--debug-prerender` | Debug prerender errors in development. |
| `--debug-build-paths=` | Build only specific routes for debugging. |
| `--experimental-cpu-prof` | Enables CPU profiling using V8's inspector. Profiles are saved to `.next/cpu-profiles/` on exit. |
### `next start` options
`next start` starts the application in production mode. The application should be compiled with [`next build`](#next-build-options) first.
The following options are available for the `next start` command:
| Option | Description |
| --------------------------------------- | --------------------------------------------------------------------------------------------------------------- |
| `-h` or `--help` | Show all available options. |
| `[directory]` | A directory on which to start the application. If no directory is provided, the current directory will be used. |
| `-p` or `--port ` | Specify a port number on which to start the application. (default: 3000, env: PORT) |
| `-H` or `--hostname ` | Specify a hostname on which to start the application (default: 0.0.0.0). |
| `--keepAliveTimeout ` | Specify the maximum amount of milliseconds to wait before closing the inactive connections. |
| `--experimental-cpu-prof` | Enables CPU profiling using V8's inspector. Profiles are saved to `.next/cpu-profiles/` on exit. |
### `next info` options
`next info` prints relevant details about the current system which can be used to report Next.js bugs when opening a [GitHub issue](https://github.com/vercel/next.js/issues). This information includes Operating System platform/arch/version, Binaries (Node.js, npm, Yarn, pnpm), package versions (`next`, `react`, `react-dom`), and more.
The output should look like this:
```bash filename="Terminal"
Operating System:
Platform: darwin
Arch: arm64
Version: Darwin Kernel Version 23.6.0
Available memory (MB): 65536
Available CPU cores: 10
Binaries:
Node: 20.12.0
npm: 10.5.0
Yarn: 1.22.19
pnpm: 9.6.0
Relevant Packages:
next: 15.0.0-canary.115 // Latest available version is detected (15.0.0-canary.115).
eslint-config-next: 14.2.5
react: 19.0.0-rc
react-dom: 19.0.0
typescript: 5.5.4
Next.js Config:
output: N/A
```
The following options are available for the `next info` command:
| Option | Description |
| ---------------- | ---------------------------------------------- |
| `-h` or `--help` | Show all available options |
| `--verbose` | Collects additional information for debugging. |
### `next telemetry` options
Next.js collects **completely anonymous** telemetry data about general usage. Participation in this anonymous program is optional, and you can opt-out if you prefer not to share information.
The following options are available for the `next telemetry` command:
| Option | Description |
| ------------ | --------------------------------------- |
| `-h, --help` | Show all available options. |
| `--enable` | Enables Next.js' telemetry collection. |
| `--disable` | Disables Next.js' telemetry collection. |
Learn more about [Telemetry](/telemetry).
### `next typegen` options
`next typegen` generates TypeScript definitions for your application's routes without performing a full build. This is useful for IDE autocomplete and CI type-checking of route usage.
Previously, route types were only generated during `next dev` or `next build`, which meant running `tsc --noEmit` directly wouldn't validate your route types. Now you can generate types independently and validate them externally:
```bash filename="Terminal"
# Generate route types first, then validate with TypeScript
next typegen && tsc --noEmit
# Or in CI workflows for type checking without building
next typegen && npm run type-check
```
The following options are available for the `next typegen` command:
| Option | Description |
| ------------- | -------------------------------------------------------------------------------------------- |
| `-h, --help` | Show all available options. |
| `[directory]` | A directory on which to generate types. If not provided, the current directory will be used. |
Output files are written to `/types` (typically: `.next/dev/types` or `.next/types`, see [`isolatedDevBuild`](/docs/app/api-reference/config/next-config-js/isolatedDevBuild)):
```bash filename="Terminal"
next typegen
# or for a specific app
next typegen ./apps/web
```
Additionally, `next typegen` generates a `next-env.d.ts` file. We recommend adding `next-env.d.ts` to your `.gitignore` file.
The `next-env.d.ts` file is included into your `tsconfig.json` file, to make Next.js types available to your project.
To ensure `next-env.d.ts` is present before type-checking run `next typegen`. The commands `next dev` and `next build` also generate the `next-env.d.ts` file, but it is often undesirable to run these just to type-check, for example in CI/CD environments.
> **Good to know**: `next typegen` loads your Next.js config (`next.config.js`, `next.config.mjs`, or `next.config.ts`) using the production build phase. Ensure any required environment variables and dependencies are available so the config can load correctly.
### `next upgrade` options
`next upgrade` upgrades your Next.js application to the latest version.
The following options are available for the `next upgrade` command:
| Option | Description |
| ----------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------- |
| `-h, --help` | Show all available options. |
| `[directory]` | A directory with the Next.js application to upgrade. If not provided, the current directory will be used. |
| `--revision ` | Specify a Next.js version or tag to upgrade to (e.g., `latest`, `canary`, `15.0.0`). Defaults to the release channel you have currently installed. |
| `--verbose` | Show verbose output during the upgrade process. |
### `next experimental-analyze` options
`next experimental-analyze` analyzes your application's bundle output using [Turbopack](/docs/app/api-reference/turbopack). This command helps you understand the size and composition of your bundles, including JavaScript, CSS, and other assets. This command doesn't produce an application build.
```bash filename="Terminal"
npx next experimental-analyze
```
By default, the command starts a local server after analysis completes, allowing you to explore your bundle composition in the browser. The analyzer lets you:
- Filter bundles by route and switch between client and server views
- View the full import chain showing why a module is included
- Trace imports across server-to-client component boundaries and dynamic imports
See [Package Bundling](/docs/app/guides/package-bundling#optimizing-large-bundles) for optimization strategies.
To write the analysis output to disk without starting the server, use the `--output` flag. The output is written to `.next/diagnostics/analyze` and contains static files that can be copied elsewhere or shared with others:
```bash filename="Terminal"
# Write output to .next/diagnostics/analyze
npx next experimental-analyze --output
# Copy the output for comparison with a future analysis
cp -r .next/diagnostics/analyze ./analyze-before-refactor
```
The following options are available for the `next experimental-analyze` command:
| Option | Description |
| --------------- | --------------------------------------------------------------------------------------------------------------------------------------------- |
| `-h, --help` | Show all available options. |
| `[directory]` | A directory on which to analyze the application. If not provided, the current directory will be used. |
| `--no-mangling` | Disables [mangling](https://en.wikipedia.org/wiki/Name_mangling). This may affect performance and should only be used for debugging purposes. |
| `--profile` | Enables production [profiling for React](https://react.dev/reference/react/Profiler). This may affect performance. |
| `-o, --output` | Write analysis files to disk without starting the server. Output is written to `.next/diagnostics/analyze`. |
| `--port ` | Specify a port number to serve the analyzer on. (default: 4000, env: PORT) |
## Examples
### Debugging prerender errors
If you encounter prerendering errors during `next build`, you can pass the `--debug-prerender` flag to get more detailed output:
```bash filename="Terminal"
next build --debug-prerender
```
This enables several experimental options to make debugging easier:
- Disables server code minification:
- `experimental.serverMinification = false`
- `experimental.turbopackMinify = false`
- Generates source maps for server bundles:
- `experimental.serverSourceMaps = true`
- Enables source map consumption in child processes used for prerendering:
- `enablePrerenderSourceMaps = true`
- Continues building even after the first prerender error, so you can see all issues at once:
- `experimental.prerenderEarlyExit = false`
This helps surface more readable stack traces and code frames in the build output.
> **Warning**: `--debug-prerender` is for debugging in development only. Do not deploy builds generated with `--debug-prerender` to production, as it may impact performance.
### Building specific routes
You can build only specific routes in the App and Pages Routers using the `--debug-build-paths` option. This is useful for faster debugging when working with large applications. The `--debug-build-paths` option accepts comma-separated file paths and supports glob patterns:
```bash filename="Terminal"
# Build a specific route
next build --debug-build-paths="app/page.tsx"
# Build more than one route
next build --debug-build-paths="app/page.tsx,pages/index.tsx"
# Use glob patterns
next build --debug-build-paths="app/**/page.tsx"
next build --debug-build-paths="pages/*.tsx"
```
### Changing the default port
By default, Next.js uses `http://localhost:3000` during development and with `next start`. The default port can be changed with the `-p` option, 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.
### Using HTTPS during development
For certain use cases like webhooks or authentication, you can use [HTTPS](https://developer.mozilla.org/en-US/docs/Glossary/HTTPS) to have a secure environment on `localhost`. Next.js can generate a self-signed certificate with `next dev` using the `--experimental-https` flag:
```bash filename="Terminal"
next dev --experimental-https
```
With the generated certificate, the Next.js development server will exist at `https://localhost:3000`. The default port `3000` is used unless a port is specified with `-p`, `--port`, or `PORT`.
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`](https://github.com/FiloSottile/mkcert). In production, use properly issued certificates from trusted authorities.
### Configuring a timeout for downstream proxies
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
```
### Passing Node.js arguments
You can pass any [node arguments](https://nodejs.org/api/cli.html#cli_node_options_options) to `next` commands. For example:
```bash filename="Terminal"
NODE_OPTIONS='--throw-deprecation' next
NODE_OPTIONS='-r esm' next
NODE_OPTIONS='--inspect' next
```
### CPU profiling
You can capture CPU profiles to analyze performance bottlenecks in your Next.js application. The `--experimental-cpu-prof` flag enables V8's built-in CPU profiler and saves profiles to `.next/cpu-profiles/` when the process exits:
```bash filename="Terminal"
# Profile the build process
next build --experimental-cpu-prof
# Profile the dev server (profile saved on Ctrl+C or SIGTERM)
next dev --experimental-cpu-prof
# Profile the production server
next start --experimental-cpu-prof
```
The generated `.cpuprofile` files can be opened in Chrome DevTools (Performance tab → Load profile) or other V8-compatible profiling tools.
> **Good to know**: Profile files are named with a descriptive prefix and timestamp. The profiles generated depend on the command:
>
> **`next dev`:**
>
> - `dev-main-*` - Parent process (dev server orchestration)
> - `dev-server-*` - Child server process (request handling and rendering) - this is typically what you want to analyze
>
> **`next build` (Turbopack):**
>
> - `build-main-*` - Main build orchestration process
> - `build-turbopack-*` - Turbopack compilation worker
>
> **`next build` (Webpack):**
>
> - `build-main-*` - Main build orchestration process
> - `build-webpack-client-*` - Client bundle compilation worker
> - `build-webpack-server-*` - Server bundle compilation worker
> - `build-webpack-edge-server-*` - Edge runtime compilation worker
>
> **`next start`:**
>
> - `start-main-*` - Production server process
| Version | Changes |
| --------- | ------------------------------------------------------------------------------- |
| `v16.1.0` | Add the `next experimental-analyze` command |
| `v16.0.0` | The JS bundle size metrics have been removed from `next build` |
| `v15.5.0` | Add the `next typegen` command |
| `v15.4.0` | Add `--debug-prerender` option for `next build` to help debug prerender errors. |