Ktor is a Kotlin framework for creating web servers (and clients).
Unlike other frameworks, Ktor is written entirely in Kotlin and can therefore use language features such as Coroutines, reified Generics and Extension Functions more effectively.
With little overhead, fast results and good performance, Ktor is especially interesting for microservices.
If you are bored with Spring, you will find what you are looking for here. All others learn at least something new.