Want to advertise a light-weight server microframework for HTTP services we've been using in production for over a year: Jooby. 1.x has been around for many years and to my mind has a great balance between noninvasiveness (you can easily move off jooby as a framework should you decide to do so), productivity and lightness, but still with great basic feature set. It also has a nice Kotlin DSL for HTTP routes. Tastefully built in my opinion, and you go for a more annotation/injection free style of programming for microservices where application logic code can be given a greater focus because the rest "never gets in the way". Good set of plugins for common use cases. Now 2.x is under development, and a notable feature is Kotlin coroutine support 1.x: https://jooby.org/ (We've been using it for over a year in production) 2.x: https://jooby.io/ (Now with Kotlin coroutines)

FYI, I covered Jooby in my Kotlin server frameworks session at KotlinConf last year...

I really am not a fan of annotation style things so I'll remember this one :)