I love Zulip. I think it’s the best platform out there asynchronous communication in big communities. There are many reasons it’s great, but if you’re not familiar with it, I’ll list the 2 biggest in my opinion
All messages are grouped by topic and you can browse a feed (“stream”) of topics instead of a single feed of messages. This means that you can leave for a week and come back, and quickly see if anything happened that you might be interested in. On other messaging platforms, you pretty much just have to accept that you’re never going to know what happened unless you want to scroll back through tons and tons of messages you don’t care about.
It’s open source!
You can read more about Zulip’s features here
You can join at https://nixcommunity.zulipchat.com.
I’ve currently set up a few channels mimicking the Discord. I’m sure people will want more. All feedback and questions are welcome!