Understanding Your Environment Variables

Environment variables keep your app customizable and flexible. Here's a quick breakdown of the variables in your .env file, what they do, and where to get the values.

Customization

These control the basics of your app's identity:

  • NEXT_PUBLIC_SITE_NAME: Your app's name. It'll show up in titles, emails, and anywhere branding matters. Example: FastStartup.
  • NEXT_PUBLIC_SITE_URL: The app's main URL (where it lives on the web). Example: faststartup.dev.
  • NEXT_PUBLIC_SUPPORT_EMAIL: The email your users can contact for support. Example: contact@faststartup.dev.
  • NEXT_PUBLIC_UNDER_MAINTENANCE: A quick toggle for maintenance mode. Set to true when you're making updates.

Database

  • DATABASE_URL: Connection string for your database. Looks like this:

    postgresql://username:password@host:port/database?schema=public

    Replace username, password, and host with your database details. If you're using PostgreSQL locally, this might be something like localhost:5432.

Authentication

Auth Secret

  • AUTH_SECRET: A secret key used for things like signing tokens. Find more details here: AuthJS Docs.

Google Auth

  • AUTH_GOOGLE_ID and AUTH_GOOGLE_SECRET: These are your Google OAuth credentials. Get them by setting up a project in the Google API Console.

Resend (Email Sending)

Resend handles your app's emails (like password resets or welcome messages):

  • AUTH_RESEND_KEY: Your Resend API key. Create an account at resend.com to get it.
  • NEXT_PUBLIC_RESEND_EMAIL: The email address your app uses to send messages (e.g., noreply@faststartup.dev). You'll need to configure this in Resend. See their domain setup docs.

Stripe (Payments)

Stripe powers payments for your app:

  • STRIPE_PUBLISHABLE_KEY: Public key for Stripe. Safe to share on the frontend.
  • STRIPE_SECRET_KEY: Keep this one private. It's used to interact with Stripe's API on the backend.
  • STRIPE_WEBHOOK_SECRET: Verifies events from Stripe (like payment confirmations). Find it in your Stripe Dashboard.

Analytics (Optional)

Analytics help you understand how users interact with your app. These are optional—if they're empty, analytics scripts won't run.

  • NEXT_PUBLIC_GOOGLE_ANALYTICS_ID: Your Google Analytics tracking ID.
  • NEXT_PUBLIC_HOTJAR_ID: Hotjar ID for user session recordings.
  • NEXT_PUBLIC_SIMPLE_ANALYTICS_ENABLED: Toggle Simple Analytics with true or false.

Full config

# --- CUSTOMIZATION ---

NEXT_PUBLIC_SITE_NAME="FastStartup"
NEXT_PUBLIC_SITE_URL="faststartup.dev"
NEXT_PUBLIC_SUPPORT_EMAIL="contact@faststartup.dev"
NEXT_PUBLIC_UNDER_MAINTENANCE=false

# --- DATABASE ---

DATABASE_URL="postgresql://johndoe:randompassword@localhost:5432/mydb?schema=public"

# --- AUTHENTICATION ---

AUTH_SECRET=""
AUTH_GOOGLE_ID="client id"
AUTH_GOOGLE_SECRET="client secret"

# --- RESEND ---

AUTH_RESEND_KEY=abc123
NEXT_PUBLIC_RESEND_EMAIL="noreply@faststartup.dev"

# --- STRIPE ---

STRIPE_PUBLISHABLE_KEY="123"
STRIPE_SECRET_KEY="123"
STRIPE_WEBHOOK_SECRET="123"

# --- ANALYTICS ---

NEXT_PUBLIC_GOOGLE_ANALYTICS_ID=
NEXT_PUBLIC_HOTJAR_ID=
NEXT_PUBLIC_SIMPLE_ANALYTICS_ENABLED=false

Wrapping Up

Not every variable here is mandatory—just fill in what you need. And remember: sensitive values (like DATABASE_URL or STRIPE_SECRET_KEY) should never be exposed to the public. Keep them safe in your backend.