Implementing Resource Server in OAuth2 with Spring Boot

In this blog post, we will walk you through the process of setting up a resource server in OAuth2 using Spring Boot. By the end of this guide, you will have a fully functional resource server that is protected by OAuth2 and can be used to secure your APIs.

What is a Resource Server?

A resource server is the server that hosts and protects your APIs. In OAuth2, it is responsible for validating access tokens and ensuring that only authorized users have access to your protected resources.


Before we dive into the details of setting up a resource server in OAuth2 with Spring Boot, there are a few prerequisites you should be familiar with:

  • Basic knowledge of OAuth2
  • Familiarity with the Spring framework
  • Understanding of the Maven build system

Creating a Spring Boot Project

To get started, we will create a new Spring Boot project using the Spring Initializer. Follow these steps to create a new project:

  1. Go to the Spring Initializer website
  2. Select the latest version of Spring Boot
  3. Choose the following dependencies:
    • Spring Web
    • Spring Security
    • Spring Security OAuth2 Resource Server
  4. Give your project a name, such as “oauth2-resource-server”
  5. Download the project and extract it to your local machine

Configuring the Resource Server

The next step is to configure the resource server. This is done in the file, which is located in the src/main/resources directory.

Add the following properties to the file:

This property tells the resource server where to find the JWT (JSON Web Token) issuer. The issuer is responsible for signing the access tokens that will be used to access the protected resources.

Securing the API

Now that we have configured the resource server, we can secure our API by adding the following annotation to our controller class:

public String getProtectedResource() {
    return "This is a protected resource";

This annotation ensures that only requests with a valid access token that has the read scope will be able to access the protected resource.

Verifying the Access Token

To verify the access token, we need to add the following code to our controller class:

private String issuerUri;

public Map<String, Object> verifyToken(@RequestParam("token") String token) throws Exception {
    Jwt jwt = JwtHelper.decodeAndVerify(token, new RsaVerifier(issuerUri));
    Map<String, Object> claims = new ObjectMapper().readValue(jwt.getClaims(), Map.class);
    return claims;

This code decodes the JWT and returns its claims as a map. The claims contain information about the user and the scopes associated with the access token.

Testing the Resource Server

To test our resource server, we can use a tool like Postman to make a request to our protected resource. Follow these steps to test your resource server:

  1. Start the resource server by running the main method in your Application class
  2. Open Postman and make a GET request to http://localhost:8080/protected-resource
  3. You should receive a 401 Unauthorized response, as the request does not contain a valid access token
  4. To add a valid access token, go to the Authorization tab in Postman and select Bearer Token from the Type dropdown
  5. Paste your access token in the Token field and send the request again
  6. You should now receive a 200 OK response with the message This is a protected resource

Additionally, you can also enhance the security of your resource server by adding additional OAuth2 features such as refreshing the access token, revoking the token, or adding more complex authorization rules to determine who has access to your protected resources.

OAuth2 is a powerful and flexible framework for securing APIs, and implementing a resource server in OAuth2 with Spring Boot is a straightforward process. Whether you are building a simple API or a complex web application, using OAuth2 can help you ensure that your data and resources are secure and protected.


In this guide, we have shown you how to implement a resource server in OAuth2 with Spring Boot. We covered the process of creating a Spring Boot project, configuring the resource server, securing the API, and verifying the access token.

By following this guide, you should now have a solid understanding of how to implement a resource server in OAuth2 with Spring Boot. If you have any questions or run into any issues, please feel free to reach out for help. Happy coding!