just heard of http://www.mattermost.org/ , slack alternative
They seem to be great, have a nice manifesto
In 2014, Slack became popular in Silicon Valley, and our company
adopted it for messaging. But we had a problem–our archives were in our
old messaging app. After our subscription expired, the old app wanted us
to pay them to access our own data (and export still didn’t work!). We hated being
locked in. We fumed. Our discussions, our research, our analyses, and
gigabytes of our carefully tagged in-game artwork was all held for
ransom by the service we had trusted. Slack was good, but it was another
proprietary SaaS app, and we’d just been burned.
So we decided to build our own.
and tox, too