---
title: Secure Java Spring Boot API Application with ZITADEL
description: "Secure Java Spring Boot APIs using OAuth 2.0 Token Introspection with ZITADEL."
sidebar_label: Java Spring Boot
---

This integration guide shows you how to integrate **ZITADEL** into your Java Spring Boot API. It demonstrates how to secure your API using
OAuth 2 Token Introspection.

At the end of the guide you should have an API with a protected endpoint.

<Callout>
This documentation references our [example](https://github.com/zitadel/zitadel-java) on GitHub.
You can either create your own application or directly run the example by providing the necessary arguments.
</Callout>

## Set up application

Before we begin developing our API, we need to perform a few setup steps in the ZITADEL Console.
You'll need to provide some information about your app. We recommend creating a new app to start from scratch. Navigate to your Project, then add a new application at the top of the page.
Select the **API** application type and continue.

![Create app in management console](../../../public/img/java-spring/api-create.png)

Select Basic Auth for authenticating at the Introspection Endpoint.

![Create app in management console](../../../public/img/java-spring/api-create-auth.png)

After successful creation of the app, a pop-up will appear displaying the app's client ID. Copy the client ID and secret, as you will need it to configure your Java application.

![Create api key in management console](../../../public/img/java-spring/api-create-clientid-secret.png)

## Spring Setup

Now that you have configured your web application on the ZITADEL side, you can proceed with the integration of your Spring application.
This guide will reference the [example repository](https://github.com/zitadel/zitadel-java) and explain the necessary steps taken in there.
If your starting from scratch, you can use the Spring Initializer with the [following setup](https://start.spring.io/#!type=maven-project&language=java&platformVersion=3.2.1&packaging=jar&jvmVersion=17&dependencies=web,lombok,oauth2-resource-server) as a base.

### Support class

To be able to take the most out of ZITADELs RBAC, we first need to create a CustomAuthorityOpaqueTokenIntrospector, that will
customize the introspection behavior and map the role claims (`urn:zitadel:iam:org:project:roles`)
into Spring Security `authiorities`, which can be used later on to determine the granted permissions.

So in your application, create a `support/zitadel` package and in there the `CustomAuthorityOpaqueTokenIntrospector.java`:

<GithubCodeBlock url="https://github.com/zitadel/zitadel-java/blob/main/api/src/main/java/demo/app/support/zitadel/CustomAuthorityOpaqueTokenIntrospector.java" />

### Application server settings

As we have now our support class, we can now create and configure the application server itself.

In a new `config` package, create the `WebSecurityConfig.java`.
This class will take care of the authorization by require the calls on `/api/tasks` to be authorized. Any other endpoint will be public by default.
It will also use the just created CustomAuthorityOpaqueTokenIntrospector for the introspection call:

<GithubCodeBlock url="https://github.com/zitadel/zitadel-java/blob/main/api/src/main/java/demo/app/config/WebSecurityConfig.java" />

For the authorization (and the server in general) to work, the application needs some settings, so please provide the following to your `application.yml` (resources folder):

<GithubCodeBlock url="https://github.com/zitadel/zitadel-java/blob/main/api/src/main/resources/application.yml" />

Note that the `introspection-uri`, `client-id` and `client-secret` are only placeholders. You can either change them in here using the values provided by ZITADEL
or pass them later on as arguments when starting the application.

### Create example API

Create a `api` package with a `ExampleController.java` file with the content below. This will create an API with three endpoints / methods:
- `/api/healthz`: can be called by anyone and always returns `OK`
- `/api/tasks (GET)`: requires authorization and returns the available tasks
- `/api/tasks (POST)`: requires authorization with granted `admin` role and adds the task to the list

If authorization is required, the token must not be expired and the API has to be part of the audience (either client_id or project_id).

For tests we will use a Personal Access Token or the [Java Spring web example](../login/java-spring).

<GithubCodeBlock url="https://github.com/zitadel/zitadel-java/blob/main/api/src/main/java/demo/app/api/ExampleController.java" />

## Test API

In case you've created your own application and depending on your development setup you might need to build the application first:

```bash
mvn clean package -DskipTests
```

You will need to provide the `introspection-uri` ($CUSTOM_DOMAIN/oauth/v2/introspect), the `client-id` and `client-secret` previously created:

```bash
java \
  -Dspring.security.oauth2.resourceserver.opaquetoken.introspection-uri=<see configuration above> \
  -Dspring.security.oauth2.resourceserver.opaquetoken.client-id=<see configuration above> \
  -Dspring.security.oauth2.resourceserver.opaquetoken.client-secret=<see configuration above> \
  -jar api/target/api-0.0.2-SNAPSHOT.jar
```

This could look like:

```bash
java \
  -Dspring.security.oauth2.resourceserver.opaquetoken.introspection-uri=https://my-domain.zitadel.cloud/oauth/v2/introspect  \
  -Dspring.security.oauth2.resourceserver.opaquetoken.client-id=243861220627644836@example \
  -Dspring.security.oauth2.resourceserver.opaquetoken.client-secret=WJKLF3kfPOi3optkg9vi3jmfjv8oj32nfiäohj!FSC09RWUSR \
  -jar web/target/web-0.0.2-SNAPSHOT.jar
```

### Public endpoint

Now you can call the API by browser or curl. Try the healthz endpoint first:

```bash
curl -i http://localhost:18090/api/healthz
```

it should return something like:

```
HTTP/1.1 200
Vary: Origin
Vary: Access-Control-Request-Method
Vary: Access-Control-Request-Headers
X-Content-Type-Options: nosniff
X-XSS-Protection: 0
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Frame-Options: DENY
Content-Type: text/plain;charset=UTF-8
Content-Length: 2
Date: Mon, 15 Jan 2024 09:07:21 GMT

OK
```

### Task list

and the task list endpoint:

```bash
curl -i http://localhost:18090/api/tasks
```

it will return:

```
HTTP/1.1 401
Vary: Origin
Vary: Access-Control-Request-Method
Vary: Access-Control-Request-Headers
WWW-Authenticate: Bearer
X-Content-Type-Options: nosniff
X-XSS-Protection: 0
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Frame-Options: DENY
Content-Length: 0
Date: Mon, 15 Jan 2024 09:07:55 GMT
```

Get a valid access_token for the API. You can either achieve this by getting an access token with the project_id in the audience
(e.g. by using the [Spring Boot web example](../login/java-spring)) use a PAT of a service account.

If you provide a valid Bearer Token:

```bash
curl -i -H "Authorization: Bearer ${token}" http://localhost:18090/api/tasks
```

it will return an empty list:
```
HTTP/1.1 200
Vary: Origin
Vary: Access-Control-Request-Method
Vary: Access-Control-Request-Headers
X-Content-Type-Options: nosniff
X-XSS-Protection: 0
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Frame-Options: DENY
Content-Type: application/json
Transfer-Encoding: chunked
Date: Mon, 15 Jan 2024 09:15:10 GMT

[]
```

### Try to add a new task

Let's see what happens if you call the tasks endpoint:

```bash
 curl -i -X POST -H "Authorization: Bearer ${token}" -H "Content-Type: application/json" --data 'my new task' http://localhost:18090/api/tasks
```

it will complain with a permission denied (missing `admin` role):
```
HTTP/1.1 403
Vary: Origin
Vary: Access-Control-Request-Method
Vary: Access-Control-Request-Headers
WWW-Authenticate: Bearer error="insufficient_scope", error_description="The request requires higher privileges than provided by the access token.", error_uri="https://tools.ietf.org/html/rfc6750#section-3.1"
X-Content-Type-Options: nosniff
X-XSS-Protection: 0
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Frame-Options: DENY
Content-Length: 0
Date: Mon, 15 Jan 2024 09:24:39 GMT
```

### Add administrator role

So let's create the role and grant it to the user. To do so, go to your project in ZITADEL Management Console
and create the role by selecting `Roles` in the navigation and then clicking on the `New Role` button.
Finally, create the role as shown below:

![Create project role in management console](../../../public/img/java-spring/api-project-role.png)

After you have created the role, let's grant it to the user who requested the tasks.
Click on `Role Assignments` in the navigation and create a new one by selecting the user and the `admin` role.
After successful creation, it should look like:

![Created role assignment in management console](../../../public/img/java-spring/api-project-auth.png)

So you should now be able to add a new task:

```bash
curl -i -X POST -H "Authorization: Bearer ${token}" -H "Content-Type: application/json" --data 'my new task' http://localhost:18090/api/tasks
```

which will report back the successful addition:
```
HTTP/1.1 200
Vary: Origin
Vary: Access-Control-Request-Method
Vary: Access-Control-Request-Headers
X-Content-Type-Options: nosniff
X-XSS-Protection: 0
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Frame-Options: DENY
Content-Type: application/json
Content-Length: 10
Date: Mon, 15 Jan 2024 09:26:11 GMT

task added
```

Let's now retrieve the task list again:

```bash
curl -i -H "Authorization: Bearer ${token}" http://localhost:18090/api/tasks
```

As you can see your new task is listed:
```
HTTP/1.1 200
Vary: Origin
Vary: Access-Control-Request-Method
Vary: Access-Control-Request-Headers
X-Content-Type-Options: nosniff
X-XSS-Protection: 0
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Frame-Options: DENY
Content-Type: application/json
Transfer-Encoding: chunked
Date: Mon, 15 Jan 2024 09:26:48 GMT

["my new task"]
```
