I was thinking about implementing slack at our workplace, this looks like it might be a nice open source alternative.
Anyone running this at a medium-sized company?
Anyone running this at a medium-sized company?
Then riot.im as client for the phones and web.
It's basically a personal IRC client and lacks most of the features you would expect from Slack (media upload, user management, editing/deleting messages, public channels...).
Take a look at Rocket Chat and Zulip instead.
Of course, IRC can do all of that (much better than Slack, from a technical point of view). But IRC + The Lounge is not a drop-in replacement for Slack.