# How to change the default port in Spring Boot

By Atta Ur Rehman Shah (https://attacomsian.com/about). Published Feb 12, 2020, updated Oct 11, 2022. Topics: Spring Boot.
Canonical URL: https://attacomsian.com/blog/spring-boot-change-default-port

> A quick article to learn how to change the default port for a Spring Boot application.

In this article, you'll learn how to change the default port in Spring Boot. By default, the embedded web server uses port `8080` to start the Spring Boot application. There are several ways available to change that port, as explained below.

## Change port using configuration files

The easiest and faster way to change the default port in Spring Boot is by overriding the default value in a configuration file. Spring Boot uses the `server.port` configuration property to specify the port.

The following example shows how you can specify a custom port in the `application.properties` file:

```properties
server.port=8888
```

Now the server will launch the application on port `8888`. For `application.yml`, you need to add the following:

```yml
server:
    port: 8888
```

Spring Boot automatically loads the above files if placed in the `src/main/resources/` folder.

## Change port using system property

You can also set a system property to change the default port of the Spring Boot application. All you need to do is set an environment variable called `SERVER_PORT` on the operating system where the server will be started.

For a Unix-based operating system, type the following command to set an environment variable:

```bash
export SERVER_PORT=8888
```

For **Windows** operating system, you have to use the following command:

```bash
setx SERVER_PORT 8888
```

## Change port using command-line arguments

Another way to change the default port in Spring Boot is by using the command-line arguments while launching the application. For example, if you are packaging and running the application as a jar file, you can set the `server.port` argument with the Java command:

```bash
$ java -jar spring-boot-app.jar --server.port=8888
```

The above command is equivalent to the following:

```bash
$ java -jar -Dserver.port=8888 spring-boot-app.jar
```

## Change port using programmatic configuration

You can change the default port programmatically while starting the application or customizing the embedded server configuration.

To set the port in the main application class while starting the application, use the following code:

```java
@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication application = new SpringApplication(Application.class);
        application.setDefaultProperties(Collections.singletonMap("server.port", "8888"));
        application.run(args);
    }

}
```

To customize the embedded server configuration, you have to implement the `WebServerFactoryCustomizer` interface  as shown below:

```java
@Component
public class PropertiesCustomizer
        implements WebServerFactoryCustomizer<ConfigurableWebServerFactory> {

    @Override
    public void customize(ConfigurableWebServerFactory factory) {
        factory.setPort(8888);
    }
}
```

## Environment-specific ports

If your application is deployed in different environments, you may want to run it on separate ports.

For example, you may want to use port `8888` for development and port `8889` for the production environment for your Spring Boot application.

To achieve this, create a new file called `application-dev.properties` for the development environment in the `src/main/resources/` folder with the following content:

```properties
server.port=8888
```

Next, create a `application-prod.properties` file for the production environment with a different port:

```properties
server.port=8889
```

To activate the desired Spring Boot profile, add the following property to the `application.properties` file:

```properties
# spring boot active profile - div or prod
spring.profiles.active=dev
```

That's it. Spring Boot will automatically pick the server port for the currently active profile.

## Change to a random port

If you want to run the Spring Boot application on any available random port, just set the `server.port=0` property. The embedded web server will look for a free port using OS natives to prevent clashes and assign it to the application.