While created for the purpose of ninenines-related projects, it is open to any kind of open source project written in or usable from Erlang.
As I understand it, it is targeted less at user questions or user-maintainer interactions (this is what this forum and the Erlang Slack already covers) but mainly at interactions between maintainers and contributors (tl;dr, like how it was with IRC back in the old days (and gosh, I miss the old days )).
One of the unfortunate things about Discord for smaller, slower communities is that invite links may expire before people see them. I’m assuming that’s what happened here. Or the link was pasted wrong and was never valid.
The linked website has been updated with an invite link that should not expire. READMEs of projects where it is mentioned and the erlang.mk website will follow.