The site looks great, but when I clicked the "Start Trial" button and scanned through the categories, there were literally none that applied to me (non-web backend/distributed systems, Rust/C++/Java). That gives me the impression that this site isn't really meant for people like me.
We do have a functional programming remote jobs and java category as well. Only thing I've not enabled that in the list of categories. You can choose any of the categories and signup. Later send me an email with the custom preference and I'll enable that for you in the backends.