Tapir looks nice, didn't know about. Can I ask, do you use it together with Netty? How fast is it for you? (if you happen to have benchmarked it)

Have you tried Vertx with Scala? (Or Spring + Scala, or sth else?)

> The introduction of Guice

Personally I've wired everything statically at compile time, zero dependency injections. (Felt as if what I did went a tiny bit against the framework, but works fine.)