https://stackoverflow.com/questions/28006501/how-to-specify-prefix-for-all-controllers-in-spring-bootYou can provide a mapping to root context path of your spring boot application to /api/* in your custom configuration.
```java
import org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration;
import org.springframework.boot.context.embedded.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.DispatcherServlet;
@
Configurationpublic class DispatcherServletCustomConfiguration {
    @
Bean    public DispatcherServlet dispatcherServlet() {
        return new DispatcherServlet();
    }
    @
Bean    public ServletRegistrationBean dispatcherServletRegistration() {
        ServletRegistrationBean registration = new ServletRegistrationBean(
                dispatcherServlet(), "/api/");
        registration.setName(DispatcherServletAutoConfiguration.DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME);
        return registration;
    }
}
```
or add this to your application.properties in src\main\resources folder
```
server.contextPath=/api/*
```