Mattermost CEO here, You're right that it does take some effort to self manage. We try to make it as easy as we can with a single Linux binary and lots of docu

Mattermost CEO here, You're right that it does take some effort to self manage. We try to make it as easy as we can with a single Linux binary and lots of documentation. One of the most common scenarios for Mattermost is deploying into a private network, that's invisible to SaaS services. The software that runs manufacturing plants should never touch the internet. Neither should the backends of financial services companies, and many other industries. Developers in those companies need to have some way to collaborate, and integrate with their DevOps toolchains and legacy backends, and Mattermost is getting increasingly popular there. Every open source Mattermost server has all the core features of Slack, including Slack-compatible keyboard shortcuts, and Slack integrations via webhooks. Every Mattermost server can host hundreds of Slack-compatible teams, and every month over 10,000 servers are downloaded. Also, if you've installed GitLab already, you just turn on Mattermost as a feature in omnibus. It's really simple to start. When you get to a few hundred users and IT needs to add some more admin and permissions there's some additional setup, but then you can go to hundreds or thousands of users from that setup.