Zulip

Zulip organises discussions into topics, helping distributed groups follow conversations and return to relevant information without relying on one chronological channel.

It is useful for organising work around an actual item, shared process or collaboration task. Its main areas include Topic-based messaging, Team conversations and Open source software, helping a visitor understand the role the product can play within an individual or team workflow.

The official Zulip site includes sections for Security, Integrations and Teams.