Environment Variables - Front-end Project

Overview

Environment variables are used to configure the application for different environments (development, staging, production) without changing code. They are typically stored in .env files.

Environment variables prefixed with NEXT_PUBLIC_ are exposed to the browser. All other variables are only available on the server side.

API Configuration

NEXT_PUBLIC_API_URL

Base URL for the backend API.

NEXT_PUBLIC_API_URL

string

required

The base URL for all API requests

Example Values

NEXT_PUBLIC_API_URL=http://localhost:3001/api

NEXT_PUBLIC_API_VERSION

API version to use.

NEXT_PUBLIC_API_VERSION

string

API version identifier (default: “v1”)

Example

NEXT_PUBLIC_API_VERSION=v2

API_TIMEOUT

Request timeout in milliseconds.

API_TIMEOUT

number

Maximum time to wait for API responses (default: 30000)

Example

API_TIMEOUT=60000

Authentication

NEXT_PUBLIC_AUTH_ENABLED

Enable or disable authentication.

NEXT_PUBLIC_AUTH_ENABLED

boolean

Whether authentication is required (default: true)

Example

NEXT_PUBLIC_AUTH_ENABLED=true

JWT_SECRET

Secret key for JWT token signing (server-side only).

JWT_SECRET

string

required

Secret key used to sign and verify JWT tokens

This variable should NEVER be exposed to the client. Do not prefix with NEXT_PUBLIC_.

Example

JWT_SECRET=your-super-secret-key-change-in-production

SESSION_SECRET

Secret for session encryption (server-side only).

SESSION_SECRET

string

required

Secret key for encrypting session data

Example

SESSION_SECRET=another-secret-key-for-sessions

TOKEN_EXPIRY

JWT token expiration time.

TOKEN_EXPIRY

string

Token expiration duration (default: “1h”)

Example

TOKEN_EXPIRY=24h

OAuth Providers

GOOGLE_CLIENT_ID

Google OAuth client ID.

GOOGLE_CLIENT_ID

string

Client ID from Google Cloud Console

GOOGLE_CLIENT_SECRET

Google OAuth client secret (server-side only).

GOOGLE_CLIENT_SECRET

string

Client secret from Google Cloud Console

Example

GOOGLE_CLIENT_ID=123456789-abcdef.apps.googleusercontent.com
GOOGLE_CLIENT_SECRET=GOCSPX-abc123def456

GITHUB_CLIENT_ID

GitHub OAuth client ID.

GITHUB_CLIENT_ID

string

Client ID from GitHub OAuth App

GITHUB_CLIENT_SECRET

GitHub OAuth client secret (server-side only).

GITHUB_CLIENT_SECRET

string

Client secret from GitHub OAuth App

Example

GITHUB_CLIENT_ID=Iv1.1234567890abcdef
GITHUB_CLIENT_SECRET=1234567890abcdef1234567890abcdef12345678

Database

DATABASE_URL

Database connection string (server-side only).

DATABASE_URL

string

required

Full database connection URL

Example

DATABASE_URL=postgresql://user:password@localhost:5432/mydb

Analytics & Tracking

NEXT_PUBLIC_GA_ID

Google Analytics tracking ID.

NEXT_PUBLIC_GA_ID

string

Google Analytics measurement ID (e.g., G-XXXXXXXXXX)

Example

NEXT_PUBLIC_GA_ID=G-XXXXXXXXXX

NEXT_PUBLIC_SEGMENT_KEY

Segment analytics write key.

NEXT_PUBLIC_SEGMENT_KEY

string

Segment write key for analytics

Example

NEXT_PUBLIC_SEGMENT_KEY=abc123def456ghi789

Feature Flags

NEXT_PUBLIC_ENABLE_BETA_FEATURES

Enable beta/experimental features.

NEXT_PUBLIC_ENABLE_BETA_FEATURES

boolean

Toggle beta features (default: false)

NEXT_PUBLIC_ENABLE_ANALYTICS

Enable analytics tracking.

NEXT_PUBLIC_ENABLE_ANALYTICS

boolean

Toggle analytics (default: true)

NEXT_PUBLIC_ENABLE_NOTIFICATIONS

Enable push notifications.

NEXT_PUBLIC_ENABLE_NOTIFICATIONS

boolean

Toggle notifications (default: true)

Example

NEXT_PUBLIC_ENABLE_BETA_FEATURES=false
NEXT_PUBLIC_ENABLE_ANALYTICS=true
NEXT_PUBLIC_ENABLE_NOTIFICATIONS=true

File Storage

AWS_S3_BUCKET

AWS S3 bucket name (server-side only).

AWS_S3_BUCKET

string

S3 bucket for file storage

AWS_ACCESS_KEY_ID

AWS access key ID (server-side only).

AWS_ACCESS_KEY_ID

string

AWS IAM access key

AWS_SECRET_ACCESS_KEY

AWS secret access key (server-side only).

AWS_SECRET_ACCESS_KEY

string

AWS IAM secret key

AWS_REGION

AWS region.

AWS_REGION

string

AWS region (e.g., us-east-1)

Example

AWS_S3_BUCKET=my-app-uploads
AWS_ACCESS_KEY_ID=AKIAIOSFODNN7EXAMPLE
AWS_SECRET_ACCESS_KEY=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY
AWS_REGION=us-east-1

Email Service

SMTP_HOST

SMTP server hostname (server-side only).

SMTP_HOST

string

SMTP server address

SMTP_PORT

SMTP server port (server-side only).

SMTP_PORT

number

SMTP port (typically 587 or 465)

SMTP_USER

SMTP username (server-side only).

SMTP_USER

string

SMTP authentication username

SMTP_PASSWORD

SMTP password (server-side only).

SMTP_PASSWORD

string

SMTP authentication password

FROM_EMAIL

Default sender email address.

FROM_EMAIL

string

Email address to send from

Example

SMTP_HOST=smtp.gmail.com
SMTP_PORT=587
SMTP_USER=[email protected]
SMTP_PASSWORD=your-app-password
FROM_EMAIL=[email protected]

Application Settings

NODE_ENV

Current environment.

NODE_ENV

'development' | 'staging' | 'production'

required

Application environment

PORT

Server port.

PORT

number

Port for the application server (default: 3000)

NEXT_PUBLIC_APP_URL

Public application URL.

NEXT_PUBLIC_APP_URL

string

required

Full URL where the app is hosted

Example

NODE_ENV=development
PORT=3000
NEXT_PUBLIC_APP_URL=http://localhost:3000

Usage in Code

Accessing Environment Variables

// Only NEXT_PUBLIC_ prefixed variables are available
const apiUrl = process.env.NEXT_PUBLIC_API_URL;
const gaId = process.env.NEXT_PUBLIC_GA_ID;

console.log('API URL:', apiUrl);

Environment Files

File Structure

# Local development overrides (not committed to git)
NEXT_PUBLIC_API_URL=http://localhost:3001/api
DATABASE_URL=postgresql://localhost:5432/mydb_dev

The .env.local file takes precedence over other environment files and should never be committed to version control.

Validation

Validate required environment variables at startup:

const requiredEnvVars = [
  'NEXT_PUBLIC_API_URL',
  'DATABASE_URL',
  'JWT_SECRET'
];

requiredEnvVars.forEach((envVar) => {
  if (!process.env[envVar]) {
    throw new Error(`Missing required environment variable: ${envVar}`);
  }
});

export function validateEnv() {
  console.log('✓ All required environment variables are set');
}

Utilities

Configuration

​Overview

​API Configuration

​NEXT_PUBLIC_API_URL

​Example Values

​NEXT_PUBLIC_API_VERSION

​Example

​API_TIMEOUT

​Example

​Authentication

​NEXT_PUBLIC_AUTH_ENABLED

​Example

​JWT_SECRET

​Example

​SESSION_SECRET

​Example

​TOKEN_EXPIRY

​Example

​OAuth Providers

​GOOGLE_CLIENT_ID

​GOOGLE_CLIENT_SECRET

​Example

​GITHUB_CLIENT_ID

​GITHUB_CLIENT_SECRET

​Example

​Database

​DATABASE_URL

​Example

​Analytics & Tracking

​NEXT_PUBLIC_GA_ID

​Example

​NEXT_PUBLIC_SEGMENT_KEY

​Example

​Feature Flags

​NEXT_PUBLIC_ENABLE_BETA_FEATURES

​NEXT_PUBLIC_ENABLE_ANALYTICS

​NEXT_PUBLIC_ENABLE_NOTIFICATIONS

​Example

​File Storage

​AWS_S3_BUCKET

​AWS_ACCESS_KEY_ID

​AWS_SECRET_ACCESS_KEY

​AWS_REGION

​Example

​Email Service

​SMTP_HOST

​SMTP_PORT

​SMTP_USER

​SMTP_PASSWORD

​FROM_EMAIL

​Example

​Application Settings

​NODE_ENV

​PORT

​NEXT_PUBLIC_APP_URL

​Example

​Usage in Code

​Accessing Environment Variables

​Environment Files

​File Structure

​Validation

Build docs developers (and LLMs) love

Overview

API Configuration

NEXT_PUBLIC_API_URL

Example Values

NEXT_PUBLIC_API_VERSION

Example

API_TIMEOUT

Example

Authentication

NEXT_PUBLIC_AUTH_ENABLED

Example

JWT_SECRET

Example

SESSION_SECRET

Example

TOKEN_EXPIRY

Example

OAuth Providers

GOOGLE_CLIENT_ID

GOOGLE_CLIENT_SECRET

Example

GITHUB_CLIENT_ID

GITHUB_CLIENT_SECRET

Example

Database

DATABASE_URL

Example

Analytics & Tracking

NEXT_PUBLIC_GA_ID

Example

NEXT_PUBLIC_SEGMENT_KEY

Example

Feature Flags

NEXT_PUBLIC_ENABLE_BETA_FEATURES

NEXT_PUBLIC_ENABLE_ANALYTICS

NEXT_PUBLIC_ENABLE_NOTIFICATIONS

Example

File Storage

AWS_S3_BUCKET

AWS_ACCESS_KEY_ID

AWS_SECRET_ACCESS_KEY

AWS_REGION

Example

Email Service

SMTP_HOST

SMTP_PORT

SMTP_USER

SMTP_PASSWORD

FROM_EMAIL

Example

Application Settings

NODE_ENV

PORT

NEXT_PUBLIC_APP_URL

Example

Usage in Code

Accessing Environment Variables

Environment Files

File Structure

Validation