`runtimeConfig (config)`

Defines server-only and public runtime values overridable by env vars.

Since Nuxt 3.0 Spec ↗

Syntax

runtimeConfig: { ...private, public: { ...exposed } }

Parameters

Name	Type	Required	Description
`runtimeConfig`	`object`	No	Root keys are server-only; the `public` sub-object is exposed to the client. Values act as defaults.

Returns

NuxtConfig — Consumed via useRuntimeConfig() at runtime.

Examples

export default defineNuxtConfig({
  runtimeConfig: {
    apiSecret: '',
    db: { url: '' },
    public: {
      apiBase: '/api',
      siteUrl: 'https://example.com',
    },
  },
})

# .env — NUXT_ prefix overrides at runtime
NUXT_API_SECRET=prod-secret
NUXT_PUBLIC_API_BASE=https://api.example.com

Notes

Provide empty-string/placeholder defaults so the keys exist; real values come from `NUXT_*` (private) and `NUXT_PUBLIC_*` (public) environment variables at runtime, enabling the same build across environments. Never put secrets under `public`.