Fluid Chat is a free, open source team chat platform that serves as a Slack alternative. It offers channels, direct messages, threads, reactions, file sharing, and powerful search, all without per-seat costs or message history limits. You can choose to use the hosted version or self-host it on your own server with Postgres as the only hard dependency. The platform includes administrative controls like roles, retention policies, audit logs, and full data exports. With a focus on privacy and ownership.