/nuxt

Nuxt Configuration

Nuxt uses configuration files to customize application behavior. The main configuration options are nuxt.config.ts for build-time settings and app.config.ts for runtime settings.

nuxt.config.ts

The main configuration file at the root of your project:

// nuxt.config.ts
export default defineNuxtConfig({
  // Configuration options
  devtools: { enabled: true },
  modules: ['@nuxt/ui'],
})

Path Aliases

The default srcDir is app/, so path aliases resolve as:

Reference root-level paths (modules, server handlers) with ~~ or #server:

export default defineNuxtConfig({
  modules: ['~~/custom-modules/awesome.js'], // relative to rootDir
  serverHandlers: [
    { route: '/foo/**', handler: '#server/foohandler.ts' },
  ],
})

nuxt.config Loading (Nuxt 5: no more jiti)

Nuxt 5 no longer bundles jiti. nuxt.config.ts, files in modules/, and layer configs are loaded by the Node runtime directly (requires Node 22.19/24.11+, which strip types natively). Two consequences:

• Relative imports in these files need an explicit extension — write ./build/plugin.ts, not ./build/plugin (TS reports TS2835). Bare package imports are unaffected.
• Use erasable TypeScript only in config/module files — no enum, namespace, constructor parameter properties, or decorators (TS reports TS1294).

App and shared/ code go through Vite and are unaffected. Published layers/modules must ship compiled JS (a shipped config as nuxt.config.mjs). Install jiti (-D) to restore the old fallback behavior; a nuxt.schema file always needs it.

Compatibility Version

Nuxt 5 behavior is now the default. future.compatibilityVersion is mostly historical — Nuxt 4 code paths that were opt-in are now unconditional. Individual behaviors are restored via specific experimental/config options (see each section below and the upgrade notes).

Environment Overrides

Configure environment-specific settings:

export default defineNuxtConfig({
  $production: {
    routeRules: {
      '/**': { isr: true },
    },
  },
  $development: {
    // Development-specific config
  },
  $env: {
    staging: {
      // Staging environment config
    },
  },
})

Use --envName flag to select environment: nuxt build --envName staging

Runtime Config

For values that need to be overridden via environment variables:

// nuxt.config.ts
export default defineNuxtConfig({
  runtimeConfig: {
    // Server-only keys
    apiSecret: '123',
    // Keys within public are exposed to client
    public: {
      apiBase: '/api',
    },
  },
})

Override with environment variables:

# .env
NUXT_API_SECRET=api_secret_token
NUXT_PUBLIC_API_BASE=https://api.example.com

Access in components/composables:

<script setup lang="ts">
const config = useRuntimeConfig()
// Server: config.apiSecret, config.public.apiBase
// Client: config.public.apiBase only
</script>

App Config

For public tokens determined at build time (not overridable via env vars):

// app/app.config.ts
export default defineAppConfig({
  title: 'Hello Nuxt',
  theme: {
    dark: true,
    colors: {
      primary: '#ff0000',
    },
  },
})

Access in components:

<script setup lang="ts">
const appConfig = useAppConfig()
</script>

runtimeConfig vs app.config

Use runtimeConfig for secrets and values that change per environment. Use app.config for public tokens, theme settings, and non-sensitive config.

External Tool Configuration

Nuxt uses nuxt.config.ts as single source of truth. Configure external tools within it:

export default defineNuxtConfig({
  // Nitro configuration
  nitro: {
    // nitro options
  },
  // Vite configuration
  vite: {
    // vite options
    vue: {
      // @vitejs/plugin-vue options
    },
  },
  // PostCSS configuration
  postcss: {
    // postcss options
  },
})

Environment-specific Vite Config

Top-level vite options are shared. Use $client and $server to target a single Vite build:

export default defineNuxtConfig({
  vite: {
    $client: {
      build: { rollupOptions: { output: { manualChunks: { analytics: ['analytics-package'] } } } },
    },
    $server: {
      build: { sourcemap: 'inline' },
    },
  },
})

Vue Configuration

Enable Vue experimental features:

export default defineNuxtConfig({
  vue: {
    propsDestructure: true,
  },
})

Nuxt 5 Default Changes

Many former experimental flags are now on by default. Each can be reverted via the named option:

Removed options (behavior now unconditional): experimental.viteEnvironmentApi, experimental.routeTypedFetch, experimental.renderJsonPayloads, experimental.externalVue. Delete them from config.

unhead.legacy is ignored (setting it warns); Capo title sorting is always on.

Other Experimental Flags

Notable opt-in flags under experimental (see source for the full list):

export default defineNuxtConfig({
  experimental: {
    // Stream the HTML shell first, then render body progressively (better TTFB)
    ssrStreaming: true,
    // Reject fetches to paths no server route answers (true | 'isomorphic')
    strictRouteTypes: true,
    // Respond 404 for unmatched paths without loading the Vue app/plugins/middleware
    early404: true,
    // Prerender error.vue into 404.html at build time
    prerenderErrorPages: true,
    // Default options for core composables/components
    defaults: {
      nuxtLink: { prefetch: true, prefetchOn: { visibility: true } },
      useAsyncData: { deep: true },
    },
  },
})