Runtime Config

Runtime config stores values that should be available to the server runtime and optionally exposed to the browser.

Define config

export default defineResuxConfig({
  runtimeConfig: {
    apiSecret: process.env.API_SECRET,
    public: {
      appOrigin: process.env.APP_ORIGIN,
      apiBase: '/api'
    }
  }
})

Read config

<script setup lang="ts">
const config = useRuntimeConfig()
</script>

<template>
  <p>API base: {{ config.public.apiBase }}</p>
</template>

Public config

Only runtimeConfig.public is serialized to the browser payload. Keep secrets outside public.

// Safe in browser
config.public.appOrigin

// Server-only by convention
config.apiSecret

API URL resolution

For internal /api/... URLs during SSR, $fetch and apiURL use this origin priority:

1. Current request origin.
2. Public runtime origins such as appOrigin, appURL, siteURL, or origin.
3. Fallback http://localhost:3000.

Set runtimeConfig.public.appOrigin for predictable production SSR fetches behind proxies.