SkillBench OTP Backend

Node.js + Express backend for handling OTP authentication using 2Factor.in API.

🚀 Quick Start

1. Install Dependencies

cd backend-example
npm install

2. Environment Setup

cp .env.example .env

Edit .env and add your 2Factor.in API key:

TWOFACTOR_API_KEY=your-2factor-api-key-here
PORT=3001
ALLOWED_ORIGINS=http://localhost:5173,http://localhost:3000

3. Start Server

# Development (with auto-reload)
npm run dev

# Production
npm start

📡 API Endpoints

Health Check

GET /health

Get API Key (Legacy)

GET /otpget
Response: { "key": "your-api-key" }

Send OTP

POST /send-otp
Content-Type: application/json

Body:
{
  "phone": "9876543210"
}

Success Response:
{
  "success": true,
  "sessionId": "session-id-from-2factor",
  "message": "OTP sent successfully to your phone number.",
  "phone": "+919876543210"
}

Error Response:
{
  "success": false,
  "error": "Invalid phone number format. Please enter a valid 10-digit number."
}

Verify OTP

POST /verify-otp
Content-Type: application/json

Body:
{
  "sessionId": "session-id-from-send-otp",
  "otp": "123456"
}

Success Response:
{
  "success": true,
  "message": "OTP verified successfully."
}

Error Response:
{
  "success": false,
  "error": "Invalid OTP code. Please check the code and try again."
}

Legacy Endpoints

• POST /sendotp - Same as /send-otp
• POST /verifyotp - Same as /verify-otp

🛡️ Error Handling

The backend handles various error scenarios:

• Invalid phone numbers - Format validation
• DND numbers - Do Not Disturb detection
• Rate limiting - Too many requests
• Network errors - Connection issues
• API errors - 2Factor.in service issues

🔧 Configuration

Environment Variables

• TWOFACTOR_API_KEY - Your 2Factor.in API key (required)
• PORT - Server port (default: 3001)
• NODE_ENV - Environment mode (development/production)
• ALLOWED_ORIGINS - CORS allowed origins (comma-separated)

CORS Setup

The server is configured to allow requests from:

• http://localhost:5173 (Vite dev server)
• http://localhost:3000 (React dev server)

Add your frontend URL to ALLOWED_ORIGINS in .env.

📁 Project Structure

backend-example/
├── routes/
│   └── otp.js              # OTP API routes
├── services/
│   └── OTPService.js       # 2Factor.in integration
├── middleware/
│   └── errorHandler.js     # Error handling
├── server.js               # Express app setup
├── package.json
├── .env.example
└── README.md

🔄 Integration with Frontend

Update your React app's .env:

VITE_BACKEND_URL=http://localhost:3001
# Remove the test mode flag
# VITE_FORCE_TEST_MODE=true

Your React OTPService will automatically use these backend endpoints.

🐛 Troubleshooting

Common Issues

1. CORS errors: Check ALLOWED_ORIGINS in .env
2. API key errors: Verify TWOFACTOR_API_KEY is set correctly
3. Port conflicts: Change PORT in .env if 3001 is occupied
4. Network errors: Check internet connection and firewall settings

Logs

The server logs all requests and errors to console. Check terminal for debugging info.

🔐 Security Features

• Helmet.js - Security headers
• CORS - Cross-origin request protection
• Request validation - Input sanitization
• Error sanitization - No sensitive data exposure
• Rate limiting - Built into 2Factor.in API