Dropbox has open-sourced Zulip

is this something like slack?

yep - very similar but with an emphasis on self hosting.

Dropbox has great designers, surprised they couldn't have found a few hours to spruce this up in the year and a half since it was acquired :)

Slack, Zulip, this feels like we are back in 1999, when the internet was divided by ICQ, AOL Instant Messanger, Windows Live Messanger, and Yahoo Messanger. (Instant/Live was a plus back then). And the only innovation over IRC was a backlog and buddy list. I wonder when the Trillian of Slack+Zulip will come out. I hope Trillian (which still exists) is already working on it.

I was just about to try out Mattermost for our company communications. It integrates with a few things including gitlab, but Zulip seems to have a larger number of integration options, which is awesome. Anybody tried both and have thoughts on them?

I still prefer to host my own infrastructure, and I want to be able to archive and categorize a discussion (after it's happened) for searchability, but a couple of our people want an alternative to email and Google Hangouts for communications, and are pushing for Slack or XMPP. I've never been a big chat user and another of our people doesn't do chat at all (so we'd likely need some kind of email gateway for him). I'm not convinced anything exists that answers all these needs, but maybe I'm just way out of the loop.

Also, do any of these integrate with XMPP? Googling is inconclusive, but it seems neither connects to XMPP directly, which is unfortunate. I'd like to see an open standard backing whatever chat we choose.