🔐 JWT Authentication API

A simple Node.js and Express.js REST API that demonstrates JWT (JSON Web Token) Authentication using Express Middleware. This project provides a protected endpoint that can only be accessed with a valid JWT token.

📌 Features

• JWT-based Authentication
• Protected API Endpoint
• Express Middleware for Token Verification
• RESTful API Design
• Proper Error Handling
• JSON Responses

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🛠️ Tech Stack

• Node.js
• Express.js
• JSON Web Token (JWT)
• JavaScript (ES6)

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📂 Project Structure

jwt-auth-api/
│
├── middleware/
│   └── auth.js
│
├── routes/
│   └── protected.js
│
├── server.js
├── package.json
├── package-lock.json
└── .gitignore

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🚀 Installation

Clone the Repository

git clone https://github.com/<your-username>/jwt-auth-api.git

Navigate to the Project

cd jwt-auth-api

Install Dependencies

npm install

Start the Server

node server.js

or

npx nodemon server.js

The server will start at:

http://localhost:5000

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📮 API Endpoints

1️⃣ Generate JWT Token

POST

/api/login

Response

{
    "token": "your_generated_jwt_token"
}

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2️⃣ Access Protected Resource

GET

/api/protected

Headers

Authorization: Bearer <your_jwt_token>

Success Response

{
    "message": "Protected Resource Accessed Successfully",
    "user": {
        "id": 1,
        "username": "Akansha"
    }
}

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❌ Error Responses

Missing Token

{
    "message": "Token missing"
}

Invalid Token

{
    "message": "Invalid Token"
}

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🔒 Authentication Flow

1. Client sends a POST request to /api/login.
2. Server generates a JWT using jwt.sign().
3. Client receives the JWT token.
4. Client includes the token in the Authorization header.
5. Authentication middleware verifies the token using jwt.verify().
6. If the token is valid, access to the protected route is granted.
7. If the token is missing or invalid, the server returns 401 Unauthorized.

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🧪 Testing

You can test the API using:

• Postman
• Thunder Client
• Insomnia

Example Header

Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...

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📚 Concepts Demonstrated

• JWT Authentication
• Express Middleware
• REST API Development
• Route Protection
• Authorization Header Handling
• JSON Responses
• Error Handling

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📄 License

This project was developed as part of a technical interview assessment to demonstrate JWT Authentication using Node.js and Express.js.