European Alternatives to Slack

Decentralized messaging built on the Matrix protocol. Used by the French and German governments. Supports federation, bridging to other platforms.

German all-in-one team collaboration with end-to-end encryption. Chat, tasks, video calls, and documents. Data stored exclusively in Germany.

Croatian team messaging app by CAKE.com. Channels, threads, voice and video calls, screen sharing. Free plan with unlimited message history.