# Environment Variables

> Learn how to use environment variables in your Next.js project.

*Canonical: https://makerkit.dev/docs/next-fire/tutorials/environment-variables*

---

The starter project comes with three different environment variables files:

1. **.env**: this is a shared environment file. Here, you can add variables shared across all the environments.
2. **.env.development**: the configuration file loaded when running the `dev` command: by default, we add the Firebase Emulators settings to this file.
 - Use this file for your **development configuration**.
3. **.env.production**: the configuration file loaded when running the `build` command locally or deployed to Vercel.
 - Use this file for your **actual project's configuration** (without private keys!).
4. **.env.test**: this environment file is loaded when running the Cypress E2E tests. You would rarely need to use this.

Additionally, you can add another environment file named `.env.local`: this file is never added to Git and can be used to store the secrets you need during development.

{% alert type="warning" title="Never add secrets to your .env files" %}
<span className='block'>
    Never ever add secrets to your `.env` files. It's not safe, and you risk leaking confidential data.
  </span>

  <span>
    Instead, add your secrets using your Vercel Console, or use the `.env.local` file during development.
  </span>
{% /alert %}

## Adding Environment Variables

The production environment variables template looks like the below:

```bash
NEXT_PUBLIC_FIREBASE_API_KEY=
NEXT_PUBLIC_FIREBASE_PROJECT_ID=
NEXT_PUBLIC_FIREBASE_STORAGE_BUCKET=
NEXT_PUBLIC_FIREBASE_MESSAGING_SENDER_ID=
NEXT_PUBLIC_FIREBASE_APP_ID=
NEXT_PUBLIC_FIREBASE_MEASUREMENT_ID=
NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN=
NEXT_PUBLIC_SITE_URL=
NEXT_PUBLIC_APPCHECK_KEY=
NEXT_PUBLIC_REQUIRE_EMAIL_VERIFICATION=false

SERVICE_ACCOUNT_CLIENT_EMAIL=
GCLOUD_PROJECT=

## SECRET KEYS ARE BEST ADDED TO YOUR CI
SERVICE_ACCOUNT_PRIVATE_KEY=

STRIPE_SECRET_KEY=
STRIPE_WEBHOOK_SECRET=
```