JWT Authentication: Protecting Routes with Middleware

When building APIs, we often need to restrict access to certain endpoints, ensuring that only authenticated users can interact with them. JSON web tokens (JWTs) provide a secure and scalable way to handle authentication in Express.js applications.

In this lesson, we’ll learn how to implement JWT middleware to protect routes and ensure that only authorized requests are processed.

Why do we need route protection?

APIs often include endpoints that require authentication. For instance, a /profile route should only be accessible to logged-in users, and an /admin route should be restricted to users with administrative privileges. If these routes are unprotected, unauthorized users could access sensitive data or perform restricted actions.

JWT-based protection helps us:

• Verify user identity without storing session state.

• Add authorization checks directly in middleware.

• Secure routes based on roles or permissions.

Setting up JWT middleware

To enforce authentication in an Express application, we need to create a middleware function that checks for the validity of a JWT in incoming requests. This middleware should ensure that only users with valid tokens can access protected resources.