OAuth2 is a widely adopted open standard for authorization that provides a secure and flexible way to grant access to protected resources. In this guide, we will show you how to implement an OAuth2 authorization server in Spring Boot.


Before you begin, you should have the following installed:

  • Java 8 or later
  • Spring Boot 2.x
  • Maven
  • A code editor or IDE of your choice

Creating a Spring Boot Project

To get started, we need to create a new Spring Boot project. You can do this using Spring Initializer, which provides a web-based interface for creating Spring Boot projects with the desired dependencies.

Follow these steps to create your Spring Boot project:

  1. Go to start.spring.io
  2. Select Spring Boot 2.x from the Project dropdown
  3. Select OAuth2 from the Dependencies section
  4. Click the Generate button to download your project

Once you have downloaded the project, open it in your code editor or IDE and you should see the following structure:

├── pom.xml
└── src/
    └── main/
        └── java/
            └── com/
                └── example/
                    └── YourProjectApplication.java

Configuring the Authorization Server

Next, we will configure the authorization server. To do this, we will need to add the following to our YourProjectApplication.java file:

public class YourProjectApplication extends WebSecurityConfigurerAdapter {

  private BCryptPasswordEncoder passwordEncoder;

  protected void configure(ClientDetailsServiceConfigurer clients) throws Exception {
        .scopes("read", "write")

  protected void configure(HttpSecurity http) throws Exception {

  public static void main(String[] args) {
    SpringApplication.run(YourProjectApplication.class, args);

Let’s go through this code to understand what is happening.

The @EnableAuthorizationServer annotation is used to enable the authorization server in our application. The @SpringBootApplication annotation is used to indicate that this is a Spring Boot application.

The configure(ClientDetailsServiceConfigurer clients) method is used to configure the client details service. In this example, we are using an in-memory client store, which is suitable for development and testing. We are defining a single client with the ID “client” and a secret of “secret”. The client is granted authorization to use the authorization code grant type, with a scope of “read” and “write”. The redirect URI is set to “http://localhost:8081/callback“, and the access and refresh token validity are set to 3600 seconds.

The configure(HttpSecurity http) method is used to configure the security for the authorization server. In this example, we are disabling the Cross-Origin Resource Sharing (CORS) and Cross-Site Request Forgery (CSRF) protection and allowing all requests to pass through. Any other requests will require authentication.

Testing the Authorization Server

Now that we have implemented the authorization server, let’s test it to make sure it’s working as expected.

To test the authorization server, you can use a tool like Postman. Follow these steps to test the authorization server:

  1. Open Postman
  2. Create a new request
  3. Set the request type to GET
  4. Set the URL to http://localhost:8080/oauth/authorize?client_id=client&response_type=code&redirect_uri=http://localhost:8081/callback&scope=read%20write
  5. Send the request

If the authorization server is working as expected, you should be redirected to a login page. After you enter your credentials, you should be redirected to the redirect URI with an authorization code in the query string.


In this guide, we have shown you how to implement an OAuth2 authorization server in Spring Boot. This is just the start, and there is much more you can do with OAuth2 and Spring Boot, such as implementing a resource server, token refresh, and client authentication.

We hope that this guide has been helpful, and if you have any questions or comments, please feel free to reach out.

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