Just a pointless modular/extensible application I've started developing some years ago which allows you to have secure communications between peers... well... nothing special, but it's been useful for me in order to learn some Kotlin/Java features like java.io, ciphering algorithms, software design patterns, functional programming, different data structures... and many other things I can't remember, yeah, you can check that yourself.
Note: I absolutely do not recomment it for personal usage.