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App RouterAPI Referencenext.config.js Options

next.config.js Options

Next.js can be configured through a next.config.js file in the root of your project directory (for example, by package.json).

next.config.js
/** @type {import('next').NextConfig} */
const nextConfig = {
  /* config options here */
}
 
module.exports = nextConfig

next.config.js is a regular Node.js module, not a JSON file. It gets used by the Next.js server and build phases, and it's not included in the browser build.

If you need ECMAScript modules, you can use next.config.mjs:

next.config.mjs
/**
 * @type {import('next').NextConfig}
 */
const nextConfig = {
  /* config options here */
}
 
export default nextConfig

You can also use a function:

next.config.mjs
module.exports = (phase, { defaultConfig }) => {
  /**
   * @type {import('next').NextConfig}
   */
  const nextConfig = {
    /* config options here */
  }
  return nextConfig
}

Since Next.js 12.1.0, you can use an async function:

next.config.js
module.exports = async (phase, { defaultConfig }) => {
  /**
   * @type {import('next').NextConfig}
   */
  const nextConfig = {
    /* config options here */
  }
  return nextConfig
}

phase is the current context in which the configuration is loaded. You can see the available phases. Phases can be imported from next/constants:

const { PHASE_DEVELOPMENT_SERVER } = require('next/constants')
 
module.exports = (phase, { defaultConfig }) => {
  if (phase === PHASE_DEVELOPMENT_SERVER) {
    return {
      /* development only config options here */
    }
  }
 
  return {
    /* config options for all phases except development here */
  }
}

The commented lines are the place where you can put the configs allowed by next.config.js, which are defined in this file.

However, none of the configs are required, and it's not necessary to understand what each config does. Instead, search for the features you need to enable or modify in this section and they will show you what to do.

Avoid using new JavaScript features not available in your target Node.js version. next.config.js will not be parsed by Webpack, Babel or TypeScript.

This page documents all the available configuration options:

appDir

Enable the App Router to use layouts, streaming, and more.

assetPrefix

Learn how to use the assetPrefix config option to configure your CDN.

basePath

Use `basePath` to deploy a Next.js application under a sub-path of a domain.

compress

Next.js provides gzip compression to compress rendered content and static files, it only works with the server target. Learn more about it here.

devIndicators

Optimized pages include an indicator to let you know if it's being statically optimized. You can opt-out of it here.

distDir

Set a custom build directory to use instead of the default .next directory.

env

Learn to add and access environment variables in your Next.js application at build time.

eslint

Next.js reports ESLint errors and warnings during builds by default. Learn how to opt-out of this behavior here.

exportPathMap

Customize the pages that will be exported as HTML files when using `next export`.

generateBuildId

Configure the build id, which is used to identify the current build in which your application is being served.

generateEtags

Next.js will generate etags for every page by default. Learn more about how to disable etag generation here.

headers

Add custom HTTP headers to your Next.js app.

httpAgentOptions

Next.js will automatically use HTTP Keep-Alive by default. Learn more about how to disable HTTP Keep-Alive here.

images

Custom configuration for the next/image loader

incrementalCacheHandlerPath

Configure the Next.js cache used for storing and revalidating data.

logging

Configure how data fetches are logged to the console when running Next.js in development mode.

mdxRs

Use the new Rust compiler to compile MDX files in the App Router.

onDemandEntries

Configure how Next.js will dispose and keep in memory pages created in development.

optimizePackageImports

API Reference for optmizedPackageImports Next.js Config Option

output

Next.js automatically traces which files are needed by each page to allow for easy deployment of your application. Learn how it works here.

pageExtensions

Extend the default page extensions used by Next.js when resolving pages in the Pages Router.

poweredByHeader

Next.js will add the `x-powered-by` header by default. Learn to opt-out of it here.

productionBrowserSourceMaps

Enables browser source map generation during the production build.

reactStrictMode

The complete Next.js runtime is now Strict Mode-compliant, learn how to opt-in

redirects

Add redirects to your Next.js app.

rewrites

Add rewrites to your Next.js app.

serverComponentsExternalPackages

Opt-out specific dependencies from the Server Components bundling and use native Node.js `require`.

trailingSlash

Configure Next.js pages to resolve with or without a trailing slash.

transpilePackages

Automatically transpile and bundle dependencies from local packages (like monorepos) or from external dependencies (`node_modules`).

turbo

Configure Next.js with Turbopack-specific options

typedRoutes

Enable experimental support for statically typed links.

typescript

Next.js reports TypeScript errors by default. Learn to opt-out of this behavior here.

urlImports

Configure Next.js to allow importing modules from external URLs (experimental).

webpack

Learn how to customize the webpack config used by Next.js

webVitalsAttribution

Learn how to use the webVitalsAttribution option to pinpoint the source of Web Vitals issues.