Ok since we have a lot of TS people here maybe someone can help me out.

Let's say I have a simple interface with a few fields. I want to make sure incoming JSON conforms to that interface.

I realize at runtime the interface isn't there, but is there some tool I can use to compile a utility to check JSON against an interface without having to write a duplicative JSONSchema or something else?

io-ts [1] is what I think most people use for this

1: https://github.com/gcanti/io-ts