Runtime Configuration

Generally you'll want to use build-time environment variables to provide your configuration. The reason for this is that runtime configuration adds rendering / initialization overhead and is incompatible with Automatic Static Optimization.

To add runtime configuration to your app open next.config.js and add the publicRuntimeConfig and serverRuntimeConfig configs:

module.exports = {
  serverRuntimeConfig: {
    // Will only be available on the server side
    mySecret: 'secret',
    secondSecret: process.env.SECOND_SECRET, // Pass through env variables
  publicRuntimeConfig: {
    // Will be available on both server and client
    staticFolder: '/static',

Place any server-only runtime config under serverRuntimeConfig.

Anything accessible to both client and server-side code should be under publicRuntimeConfig.

A page that relies on publicRuntimeConfig must use getInitialProps to opt-out of Automatic Static Optimization. Runtime configuration won't be available to any page (or component in a page) without getInitialProps.

To get access to the runtime configs in your app use next/config, like so:

import getConfig from 'next/config'
import Image from 'next/image'

// Only holds serverRuntimeConfig and publicRuntimeConfig
const { serverRuntimeConfig, publicRuntimeConfig } = getConfig()
// Will only be available on the server-side
// Will be available on both server-side and client-side

function MyImage() {
  return (

export default MyImage