Zulip is an open-source team chat app organized by topic - threaded conversations so teams never lose track of a discussion.
Collaboration
Screenshots

Zulip
Zulip is an open-source team chat app organized by topic - unlike other chat tools, every conversation is threaded, so teams can have many parallel discussions without losing track of any of them.
Getting started
- Zulip confirms your admin account by email before your organization is created, but outgoing email isn't wired to a real mail provider by default - get in touch after checkout and we'll generate your one-time organization signup link directly (skips the email step entirely).
- Open that link, fill in your organization and admin account details, and you're in - this can take a couple of minutes on first launch while Zulip finishes setting up.
- Create streams (channels) under the gear icon -> Add a stream, then start topics within them.
- Invite teammates under the gear icon -> Invite users - note that invite emails won't be delivered either without SMTP configured, so share the invite link directly or get in touch for that too.