rsnext/docs/api-reference/next.config.js/environment-variables.md

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

Environment Variables

Examples

• With env
• With Now env

To add environment variables to the JavaScript bundle, open next.config.js and add the env config:

module.exports = {
  env: {
    customKey: 'my-value',
  },
}

Now you can access process.env.customKey in your code. For example:

function Page() {
  return <h1>The value of customKey is: {process.env.customKey}</h1>
}

export default Page

Next.js will replace process.env.customKey with 'my-value' at build time. Trying to destructure process.env variables won't work due to the nature of webpack DefinePlugin.

For example, the following line:

return <h1>The value of customKey is: {process.env.customKey}</h1>

Will end up being:

return <h1>The value of customKey is: {'my-value'}</h1>

Related

Introduction to next.config.js: Learn more about the configuration file used by Next.js.