CafeTran

I think both are not as powerful as Keyboard Maestro, but maybe someone needs some more to to play with, e.g. Sikuli(X) with image recognition.

Karabiner - a powerful and stable keyboard customizer for macOS

https://pqrs.org/osx/karabiner/

Sikuli (or maybe SikuliX)

http://www.sikuli.org/ 

Torsten: I think both are not as powerful as Keyboard Maestro

They aren't. That is, Sikulix isn't, I installed Karabiner, but I don't think I ever used it. I mentioned Sikulix a couple of years ago on the old CT forum. It's fun, free, and cross-platform (I think). As far as I can remember, it works fine (a bit slow though), as long as you open a window of an app always at the same spot on your screen. Which I don't.

H.