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🌐 Next.js Runtime Environment Configuration

Effortlessly populate your environment at runtime, not just at build time, with next-runtime-env.

🌟 Highlights:
- Isomorphic Design: Works seamlessly on both server and browser, and even in middleware.
- Next.js 13 & 14 Ready: Fully compatible with the latest Next.js features.
- .env Friendly: Use .env files during development, just like standard Next.js.

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In the modern software development landscape, the "[Build once, deploy many][build-once-deploy-many-link]" philosophy is key. This principle, essential for easy deployment and testability, is a [cornerstone of continuous delivery][fundamental-principle-link] and is embraced by the [twelve-factor methodology][twelve-factor-link]. However, front-end development, particularly with Next.js, often lacks support for this - requiring separate builds for different environments. next-runtime-env is our solution to bridge this gap in Next.js.

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next-runtime-env dynamically injects environment variables into your Next.js application at runtime. This approach adheres to the "build once, deploy many" principle, allowing the same build to be used across various environments without rebuilds.

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- Next.js 14: Use next-runtime-env@3.x for optimal caching support.
- Next.js 13: Opt for [next-runtime-env@2.x][app-router-branch-link], tailored for the App Router.
- Next.js 12/13 Page Router: Stick with [next-runtime-env@1.x][pages-router-branch-link].

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- 1.x: Next.js 12/13 Page Router
- 2.x: Next.js 13 App Router
- 3.x: Next.js 14 with advanced caching

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In your app/layout.tsx, add:

``js
// app/layout.tsx
import { PublicEnvScript } from 'next-runtime-env';

export default function RootLayout({ children }) {
return (





{children}


);
}
`

The PublicEnvScript component automatically exposes all environment variables prefixed with NEXT_PUBLIC_ to the browser. For custom variable exposure, refer to EXPOSING_CUSTOM_ENV.md.

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Access your environment variables easily:

`tsx
// app/client-page.tsx
'use client';
import { env } from 'next-runtime-env';

export default function SomePage() {
const NEXT_PUBLIC_FOO = env('NEXT_PUBLIC_FOO');
return

NEXT_PUBLIC_FOO: {NEXT_PUBLIC_FOO}

;
}
`

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Need to expose non-prefixed environment variables to the browser? Check out MAKING_ENV_PUBLIC.md.

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next-runtime-env` is proudly maintained by Expatfile.tax, the leading US expat tax e-filing software.

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Kudos to the react-env project for the inspiration, and a shoutout to @andonirdgz for the innovative context provider idea!

---

[build-url]: https://img.shields.io/github/checks-status/expatfile/next-runtime-env/main
[cov-img]: https://codecov.io/gh/expatfile/next-runtime-env/branch/main/graph/badge.svg?token=mbGgsweFuP
[cov-url]: https://codecov.io/gh/expatfile/next-runtime-env
[snyk-img]: https://snyk.io/test/github/expatfile/next-runtime-env/badge.svg
[snyk-url]: https://snyk.io/test/github/expatfile/next-runtime-env
[nextjs-env-vars-order]: https://nextjs.org/docs/basic-features/environment-variables#environment-variable-load-order
[build-once-deploy-many-link]: https://www.mikemcgarr.com/blog/build-once-deploy-many.html
[fundamental-principle-link]: https://cloud.redhat.com/blog/build-once-deploy-anywhere
[twelve-factor-link]: https://12factor.net
[pages-router-branch-link]: https://github.com/expatfile/next-runtime-env/tree/1.x
[app-router-branch-link]: https://github.com/expatfile/next-runtime-env/tree/2.x
[nextjs-env-vars]: https://nextjs.org/docs/basic-features/environment-variables
[react-env-repo]: https://github.com/andrewmclagan/react-env
[expatfile-site]: https://expatfile.tax