| Express.js | Build web servers and APIs | npm install express |
| Nodemon | Auto-restart server during development | npm install nodemon |
| Mongoose | Connect and manage MongoDB database | npm install mongoose |
| dotenv | Store environment variables (API keys, DB URL) | npm install dotenv |
| cors | Allow frontend apps to access backend APIs | npm install cors |
| jsonwebtoken | Create authentication tokens for login systems | npm install jsonwebtoken |
| bcrypt | Securely hash passwords | npm install bcrypt |
| multer | Upload files/images | npm install multer |
| nodemailer | Send emails (OTP, notifications, password reset) | npm install nodemailer |