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Flock vs Zulip: catalog facts
Flock	Zulip
Freemium Sign-up is self-serve; check the site for current plans.	Freemium The server and clients are free and open source and can be self-hosted at no cost. Zulip…
Web	Windows, macOS, Linux, Android
Channels for organising team discussion Built-in voice and video calls with screen sharing	Topic-based threading inside channels, which makes catching up genuinely practical Self-hostable, or hosted, with free plans for open-source communities
Proprietary hosted service; data lives on the vendor's servers Aimed at organisations rather than personal use	The topic model takes getting used to and needs team discipline to work The desktop client shares most of its code with the web app, so it inherits its quirks
Downloadable app, Web application, Hosted service	Downloadable app
Closed source	Open source
License not stated	License: Apache-2.0
Account needed	Account needed
Needs internet	Needs internet
Official website Full listing and sources Checked September 24, 2026	Official website Full listing and sources Checked September 21, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.