The easiest way to learn how to build a Spring application with Kotlin is to follow {spring-site-guides}/tutorials/spring-boot-kotlin/[the dedicated tutorial].
The easiest way to start a new Spring Framework project in Kotlin is to create a new Spring Boot project on start.spring.io.
Spring Framework comes with two different web stacks: Spring MVC and Spring WebFlux.
Spring WebFlux is recommended if you want to create applications that will deal with latency, long-lived connections or streaming scenarios.
For other use cases, especially if you are using blocking technologies such as JPA, Spring MVC is the recommended choice.