Securing API Calls with JWT

1. Introduction

JSON Web Tokens (JWT) are an open standard used for securely transmitting information between parties as a JSON object. This lesson will cover how to utilize JWT for securing API calls in front-end applications.

2. What is JWT?

JWT is a compact, URL-safe means of representing claims to be transferred between two parties. The claims in a JWT are encoded as a JSON object that is used as the payload of a JSON Web Signature (JWS) structure or as the plaintext of a JSON Web Encryption (JWE) structure, enabling the claims to be digitally signed or integrity protected with a Message Authentication Code (MAC) and/or encrypted.

3. How JWT Works

A JWT is typically structured in three parts: Header, Payload, and Signature. Here's how it works step-by-step:

            // Step 1: Create JWT
            const jwt = require('jsonwebtoken');
            const token = jwt.sign({ id: user.id }, 'secretKey', { expiresIn: '1h' });
        

The token can then be sent to the client and stored (often in local storage). When making a request to a secure endpoint, the client includes this token:

            fetch('https://api.example.com/protected', {
                method: 'GET',
                headers: {
                    'Authorization': `Bearer ${token}`
                }
            });
        

4. Implementing JWT in API Calls

To implement JWT, follow these steps:

1. Set up the backend to generate a JWT upon successful authentication.
2. Send the token back to the client.
3. Store the token securely in the client-side application (e.g., local storage).
4. Include the token in the `Authorization` header of your API requests.
5. Validate the token on the server for protected routes.

5. Best Practices

When working with JWT, keep these best practices in mind:

• Use HTTPS to secure your API calls.
• Keep your signing keys secure and rotate them regularly.
• Set appropriate expiration times for your tokens.
• Implement token revocation mechanisms.
• Do not store sensitive information in the JWT payload.

6. FAQ