title	emoji	colorFrom	colorTo	sdk	pinned
OTP Backend	🔐	blue	purple	docker	false

Flask OTP Backend

A Flask-based REST API that sends OTPs (One-Time Passwords) via email. The API accepts a mobile number, looks up the associated email from a database, generates a 6-digit OTP, and sends it via Resend API.

🚀 Features

• Mobile number to email lookup
• 6-digit OTP generation
• Email delivery via Resend API
• CORS enabled for frontend integration
• Production-ready with Gunicorn
• Deployable to Render.com

📋 Prerequisites

• Python 3.10+
• Resend API account (free tier available)
• Git and GitHub account
• Render.com account (for deployment)

🛠 Local Setup

1. Clone the Repository

git clone https://github.com/Pranav77722/otp.git
cd otp

2. Install Dependencies

pip install -r requirements.txt

3. Get Resend API Key

1. Sign up at resend.com
2. Go to API Keys
3. Click "Create API Key"
4. Name: OTP Backend
5. Permission: Full Access
6. Copy the API key (starts with re_...)

4. Configure Environment Variables

Create a .env file:

cp .env.example .env

Edit .env and add your Resend API key:

RESEND_API_KEY=re_your_actual_api_key_here
SENDER_EMAIL=onboarding@resend.dev

5. Run Locally

python app.py

Server will start at http://localhost:5000

🧪 Testing

Test the API using PowerShell:

$body = @{
    mobile = "9657329173"
} | ConvertTo-Json

Invoke-RestMethod -Uri "http://localhost:5000/send-otp" -Method Post -Body $body -ContentType "application/json"

Or using cURL:

curl -X POST http://localhost:5000/send-otp \
  -H "Content-Type: application/json" \
  -d '{"mobile":"9657329173"}'

Expected response:

{
  "success": true,
  "email": "ap8548328@gmail.com",
  "mobile": "9657329173",
  "message": "OTP sent"
}

🌐 Deploy to Render

Step 1: Push Code to GitHub

git add .
git commit -m "Deploy OTP backend"
git push origin main

Step 2: Create Render Web Service

1. Go to Render Dashboard
2. Click "New +" → "Web Service"
3. Connect your GitHub repository
4. Configure:
   • Name: otp-backend
   • Region: Choose closest to you
   • Branch: main
   • Runtime: Python 3
   • Build Command: pip install -r requirements.txt
   • Start Command: gunicorn app:app

Step 3: Add Environment Variables

In Render Settings → Environment:

1. Click "Add Environment Variable"
2. Add:
   • Key: RESEND_API_KEY
   • Value: Your Resend API key (from step 3 above)
3. Click "Save Changes"

Render will automatically deploy your app!

Step 4: Test Production API

Your API will be available at: https://your-service-name.onrender.com

Test it:

$body = @{
    mobile = "9657329173"
} | ConvertTo-Json

Invoke-RestMethod -Uri "https://your-service-name.onrender.com/send-otp" -Method Post -Body $body -ContentType "application/json"

📡 API Reference

Endpoint: POST /send-otp

Request:

{
  "mobile": "9657329173"
}

Success Response (200):

{
  "success": true,
  "email": "ap8548328@gmail.com",
  "mobile": "9657329173",
  "message": "OTP sent"
}

Error Responses:

400 - Invalid Request

{
  "success": false,
  "message": "Mobile number is required"
}

404 - Mobile Not Found

{
  "success": false,
  "message": "Mobile number not registered"
}

500 - Server Error

{
  "success": false,
  "message": "Failed to send email: ..."
}

📚 Database

Current users in db.py:

Mobile Number	Email
9657329173	ap8548328@gmail.com
9699883753	adi.akolkar12@gmail.com

To add more users, edit db.py:

USERS = {
    "9657329173": "ap8548328@gmail.com",
    "9699883753": "adi.akolkar12@gmail.com",
    "1234567890": "newuser@example.com"  # Add new entry
}

🔧 Configuration

Sender Email (Optional)

By default, emails are sent from onboarding@resend.dev.

To use a custom sender:

1. Own a domain (e.g., yourdomain.com)
2. Verify it in Resend dashboard
3. Add environment variable:

   SENDER_EMAIL=noreply@yourdomain.com
   

⚠️ Important Notes

• Do NOT commit .env to GitHub (it's in .gitignore)
• Free Resend tier: 3,000 emails/month, 100/day
• Render free tier: May spin down after inactivity (30 sec startup)
• For production, consider upgrading to paid tiers

📁 Project Structure

otp/
├── app.py              # Main Flask application
├── db.py               # User database (mobile → email)
├── email_service.py    # Resend email integration
├── otp_service.py      # OTP generation logic
├── firebase_init.py    # Firebase Admin SDK setup (optional)
├── requirements.txt    # Python dependencies
├── Procfile           # Render/Heroku configuration
├── Dockerfile         # Docker configuration
├── runtime.txt        # Python version
├── .env.example       # Environment template
└── README.md          # This file

🤝 Contributing

Pull requests are welcome! For major changes, please open an issue first.

📄 License

MIT License

🆘 Support

For issues or questions:

• GitHub Issues: Create an issue
• Email: Contact repository owner

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Made with ❤️ using Flask and Resend