@NewtonMark There are a bunch of alternatives, FWIW. Some try to copy Slack's features and affordances, but what won people over at $dayjob is Zulip, whose "topic" system does something a bit like Slack's "threads" a *whole* lot better. (Also installable on-prem, though metadata -- not content -- for mobile notifications does go through the mothership; avoiding even that is possible, but a little bit voodoo.)