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.
FreshRSS : FreshRSS is a self-hosted RSS and Atom feed aggregator.
Mattermost : Mattermost is a self-hosted solution for bringing all your team communication to one place, and making it searchable and accessible anywhere
