Riot : Riot allows teams to communicate across a wide range of collaboration apps. If some team members use Riot while others use IRC, Slack or Gitter, Riot ...
Zulip : Powerful slack-like open source group chat
Astuto : Astuto is a free, open source, self-hosted customer feedback tool. It helps you collect, manage and prioritize feedback from your users.
Backstage : Backstage is an open platform for building developer portals. Powered by a centralized software catalog, Backstage restores order to your microservice...
Cachet : Beautiful & simple service statuses. The open source status page system, for everyone.
Mattermost is a self-hosted solution for bringing all your team communication to one place, and making it searchable and accessible anywhere