🛡️ JWT Token Service

A simple Node.js and Express backend service that demonstrates basic usage of JWT (JSON Web Tokens).

📖 Description

This service provides a minimal yet functional example of how to:

• Generate JWT tokens with a limited lifetime (1 hour);
• Validate existing tokens;
• Refresh a token by issuing a new one based on a valid old token.

It can be used as an educational resource, a prototype for an authentication system, or a foundation for your own auth service.

---

🔧 How It Works

🔹 1. Generate a New Token (GET /token)

When making a GET request to /token, the service:

• Creates a new JWT token with the following payload:
  • userId: 1
  • username: "testuser"
  • exp: 1 hour from now (3600 seconds)
• Returns the token in a JSON response.

Useful for initial authentication or for generating a test token.

---

🔹 2. Refresh a Token (POST /token)

When making a POST request to /token, the service:

• Accepts an existing JWT token in the request body (under the token key);
• Validates the token’s signature and expiration;
• If the token is valid and not expired, issues a new token;
• If the token is missing or invalid, returns an appropriate error (400 or 401).

This simulates a basic "refresh token" mechanism to extend session time without re-authentication.

---

🧪 Example Requests

✅ Get a New Token

curl http://localhost:3333/token