Some people have mentioned they like Zulip: so here is a completely unofficial zulip instance for Racket:
It is chat service, but unlike discord or irc the chat history public.
Creation inspired by the https://plai.zulipchat.com/ for educators using the text Programming Languages: Application and Interpretation and https://spls.zulipchat.com
Let me know if you are interested in any integrations:
best regards
Stephen