Zulip

Zulip is a team chat platform built around streams and topics, where every message is threaded by topic so a long conversation reads as a tidy stack of replies rather than a wall of text. It adds powerful search, integrations with GitHub, GitLab, Jira, and other tools, a bot platform, native desktop and mobile clients, and the option to serve each organization from its own domain.

Engineering and operations groups use it for discussions that need to stay findable months later, such as incident reviews and design debates.

Self-hosting it keeps those archives on your own storage, removes per-user subscription costs, and gives you full control over backups and retention periods.