Hallå KittehJun 16, 2017
If you're not trying to leave #Slack already, here's some additional incentive:

https://social.heldscal.la/url/545072
Show threadHallå KittehJun 16, 2017
#slackalternatives #hprep

https://microca.st/clacke/comment/l11mIRDiQWikamj6hvp1wA has a bunch of discussion, but microca.st is unreliable and currently the cert is months too old, so I'll extract that information.

http://tiptoes.ca/3107-2/ mentions http://ryver.com/ryver-vs-slack/ .
Show threadHallå KittehJun 16, 2017
https://zulip.org/
http://mattermost.org/
https://matrix.org/
http://sdelements.github.io/lets-chat/
https://rocket.chat/
http://buddycloud.com/

XMPP frontends:

http://getkaiwa.com/
https://conversejs.org/
https://www.jsxc.org/
https://jwchat.org/
Show threadHallå Kitteh
https://spideroak.com/personal/semaphor
Jun 16, 2017 at 7:24amWeb
Show threadHallå KittehJun 20, 2017
I believe #movim also counts as an XMPP frontend for one-on-one or solo conversations, plus it has an asynchronous social network on top.

http://movim.eu/

That reminds me, BuddyCloud is in the wrong category in my original list, just like movim it's primarily an asynchronous social network, but probably (?) like movim (?) also has its own front-end for good old XMPP one-on-one and MUCs.
Show threadHallå KittehJun 20, 2017
s/solo/group/ :-)

Although solo is supported too. :-D