Securing a Spring Boot application with JWT (JSON Web Tokens) enables stateless authentication, enhancing both scalability and security. Here’s a step-by-step guide to implementing authentication and authorization in your Spring Boot project.

🔐 Secure Your Spring Boot Application with JWT Authentication

We’ve all been there — building applications with tight deadlines, where security often gets pushed to “later.” But, what if I told you securing your Spring Boot application can be both quick and robust? Let’s dive into how Spring Security paired with JWT can make your APIs secure and stateless.

What’s Happening Behind the Scenes?

Here’s a simplified flow to secure your app:

Here’s a step-by-step overview of how your Spring Boot application processes secure requests:

1️⃣ The AuthFilter intercepts the request and checks for the presence of a JWT in the Authorization header.
2️⃣ If a JWT is found, it extracts the token and passes it to the JwtService for validation.
3️⃣ Upon successful validation, the SecurityContextHolder is updated with the authenticated user’s details.
4️⃣ Finally, the request proceeds to the DispatcherServlet, where it is routed to the appropriate controller.

Request ➡️ AuthFilter ➡️ JwtService ➡️ SecurityContextHolder ➡️ DispatcherServlet ➡️ Controller

Step-by-Step Implementation

1️⃣ Add Dependencies

Add the following to your pom.xml or build.gradle

2️⃣ Configure Security

Create a configuration class to define your security rules:

Steps for Authentication and Authorization

1️⃣ Authentication Manager

The AuthenticationManager is the central component for verifying user credentials. Instead of directly dealing with it, we configure it using AuthenticationManagerBuilder.

2️⃣ Authorization Manager

The Authorization Manager controls access to specific endpoints based on roles, permissions, or other criteria.

Steps to Configure:

1. Define Roles/Permissions:
   Configure which roles or users can access specific endpoints.
2. Set Security Rules:
   Use authorizeRequests to define access rules for specific URL patterns.

@Override
protected void configure(HttpSecurity http) throws Exception {
    http.csrf().disable()
        .authorizeRequests()
            .antMatchers("/admin/**").hasRole("ADMIN") // Restrict /admin/* to users with ADMIN role
            .antMatchers("/user/**").hasAnyRole("USER", "ADMIN") // Restrict /user/* to USER or ADMIN roles
            .antMatchers("/authenticate").permitAll() // Public access
            .anyRequest().authenticated() // Default rule: all other endpoints require authentication
        .and()
        .sessionManagement()
            .sessionCreationPolicy(SessionCreationPolicy.STATELESS);
}

3️⃣ UserDetailsService

Implement UserDetailsService to load user details (username, password, roles) from the database or another source.

3️⃣ Set Up JWT Utility

Here’s how to generate, validate, and extract information from a JWT:

4️⃣ Build Your Authentication Endpoint

Here’s a basic controller to authenticate users:

💡 Why JWT?

JWT makes your API stateless, scalable, and secure. No more sticky sessions — just pass tokens between client and server. Pair JWT with multi-factor authentication for an even more robust setup!

💻 GitHub Repository for Securing Spring Boot Applications with JWT

You can find the complete source code for the example provided in this article here:

🔗 GitHub Repository: springsecurity

This repository includes:

• 🛡️ Authentication and Authorization setup
• 🔑 JWT generation, validation, and extraction
• 🧑‍💻 Implementation of AuthenticationManager and UserDetailsService
• 🌐 Secure endpoint configuration with role-based access

Feel free to clone, explore, and contribute! 🚀

🚀 Your Turn

What’s your go-to strategy for API security? Let’s share, learn, and grow together in this new year! Feel free to drop your thoughts or challenges in the comments — I’d love to hear them.

Here’s to a year of learning, sharing, and building better tech. Let’s make 2025 amazing! 🌟