🔐 Auth System (Node.js)

A complete backend authentication system with OTP verification, JWT authentication, and Gmail OAuth2 email integration.

---

🚀 Features

• 🔑 JWT Authentication
• 🔄 Refresh Token System
• 📧 OTP Email Verification (Gmail OAuth2)
• 🧠 Session Management
• 🚪 Logout & Logout from All Devices
• 🔒 Secure Password Handling (SHA256 - can be upgraded to bcrypt)

---

🛠 Tech Stack

• Node.js
• Express.js
• MongoDB (Mongoose)
• Nodemailer
• Google OAuth2
• JSON Web Token (JWT)

---

📁 Project Structure

auth-system-nodejs/
│── src/
│   ├── controllers/
│   ├── models/
│   ├── routes/
│   ├── services/
│   ├── utils/
│   └── config/
│
│── server.js
│── package.json
│── .gitignore

---

📦 Installation & Setup

# Clone repository
git clone https://github.com/yagnik1610/auth-system-nodejs.git

# Go to project folder
cd auth-system-nodejs

# Install dependencies
npm install

# Run server
npm run dev

---

🔑 Environment Variables

Create a .env file in root directory:

MONGO_URI=your_mongodb_uri
JWT_SECRET=your_jwt_secret

GOOGLE_CLIENT_ID=your_client_id
GOOGLE_CLIENT_SECRET=your_client_secret
GOOGLE_REFRESH_TOKEN=your_refresh_token
GOOGLE_USER=your_email@gmail.com

---

📌 API Endpoints

Method	Endpoint	Description
POST	/api/auth/register	Register user & send OTP
POST	/api/auth/verify-email	Verify OTP
POST	/api/auth/login	Login user
POST	/api/auth/refresh-token	Get new access token
POST	/api/auth/logout	Logout
POST	/api/auth/logout-all	Logout from all devices

---

🔄 Authentication Flow

1. User registers
2. OTP is sent via email
3. User verifies email using OTP
4. User logs in
5. Access token + refresh token generated
6. Session stored in database

---

🔥 Future Improvements

• ⏱ OTP Expiry
• 🔁 Resend OTP
• 🚫 Rate Limiting
• 🔐 Switch to bcrypt for password hashing
• 🎨 Frontend integration

---

👨‍💻 Author

Yagnik Vithlani

---

⭐ If you like this project

Give it a ⭐ on GitHub!