Zulip is great. One thing that I don't see mentioned that is a huge deal that you don't realize at first. The topic for a message can be changed after the fact

Zulip is great. One thing that I don't see mentioned that is a huge deal that you don't realize at first. The topic for a message can be changed after the fact and by anyone. So you are having a big discussion and at some point it veers off into some interesting tangent (or pointless flamewar). The original person didn't know it that idea was unique and had interest, but afterwards a big chunk of topic_A was actually about topic_B. So later a helpful person will go back and change the topic of the message that started it and all the replies will also move to that new topic name. This means that someone in another time zone or who was busy during the original conversation can come back later and see the ideas discussed and focus on just one ones that are interesting without having to read huge discussion threads. And the threads can be on-topic because people can prune it after-the-fact. Yes, this does mean you need to be a "team" and trust each other to make reasonable edits to the chat history. Just like a wiki, it sounds like a crazy idea, but works great in practice.