Own your data.
tl; dr - people are strange.
For instance, I reported a DoS bug that can cripple freemium communities and they basically told me "oh well". For obvious reasons I'm not going to go into details here, but I've got a script I can point at a slack freemium slack community to wipe out a lot of it's functionality that I built as a proof of concept and they just don't seem to care.
There are also huge issues with moderation and harassment on the freemium Slack. Since there is no way to block or ignore a user it gives trolls an insane amount of power (and before someone tells me that you can mute notifications from a person, I'll mention that all the troll needs to do is create a new chat room, force invite the person to it, and continue trolling to bypass it).
Personally I find it really frustrating that slack has kind of destroyed a bunch of IRC communities, but is refusing to build the tools needed to manage these replacements. As more and more freemium communities are figuring this out and migrating I imagine the people pushing Slack because it's what they are familiar with is going to drop.
http://ryver.com (free hosted, will add additional premium features later for project management)
http://riot.im (open source)
http://zulip.org (open source)
One reason for propreitary SaaS over open source used to be setup--but now that Mattermost is on Bitnami it's easier than ever to deploy Mattermost to AWS, Azure, GCP and OCP: https://bitnami.com/stack/mattermost
I'm guessing it was built a long time ago on cordova or one of those other "write once, run everywhere" frameworks where they just run everything in a WebView.
The next generation apps are much faster, and we're excited to release them soon.
Here's the source: https://github.com/mattermost/mattermost-mobile
There's instructions on how to get early access as well.
Though a little hokey, it's free for us and people really just want some sort of chat system. I've looked at rocket chat but I'm a jr level sysadmin with CTO/Sr Sysadmin boss in a Windows-only environment.
I'm a little hesitant to let it loose in our 100+ person environment but Skype for Business sucks and Slack would be too expensive.
Has anyone used that? Any pros/cons?
Features: Slack wins. Slack is usually a little ahead. Hipchat was catching up and then I just popped back with threaded convos.
Uptime: Slack wins I think. Hipchat goes down/slow kind of often. Approximately github often. I don't use Slack as intensely, but can't think of many times that slack was down aside from major internet outages.
Rooms/Channels: Hipchat has rooms, slack has channels. Basically parity in terms of group/private/team channels.
Pricing: Hipchat wins. Both have free tiers, but those are for toy groups. Hipchat is about $2/user vs $10/user for slack. Slack doesn't charge you for inactive users though (2 weeks dormant), so it can be competitive if you have a small team of actually active users.
Mobile: I find hipchat to be slower and a little worse in tiny annoying ways. For instance on my phone/watch, I get notifications for 1:1 messages and @mentions. But in hipchat, if i'm not already in the room where someone mentioned me, it doesn't show up when I open the app, even if I get there by swiping the notification. Come on hipchat!
On the bright side, the desktop client uses very little RAM compared to Slack.
The differences in Slack are emoji attached to messages and threaded replies that just came out.
i'd also love to hear from a user.
UPDATE: Err, or first copy, if you don't use Chrome as your primary browser.
With Slack you use backquotes for code. With Hipchat you type /code first.
Same service.
If you use gitlab (CE or EE), you can easily setup Mattermost with LDAP as well: https://gitlab.com/gitlab-org/gitlab-mattermost
Edit: Gitlab doesn't officially support SSO on top of SSO (AD/LDAP, etc), so its at your own peril: https://docs.mattermost.com/deployment/sso-gitlab.html