Wire is an team communication service from Switzerland with Apps for iOS, Android, Windows, macOS and Linux. The communication is end-to-end encrypted and the apps are open source.
Wire offers a free plan for up to 5 users. The paid plan "Enterprise" costs $7.65 per user/month.
Read more on the pricing page of the service.
Stackfield is a team communication service from Germany. It offers end-to-end encryption and apps for many desktop and mobile platforms. It also offers audio and video calls directly in the app.
Infomaniak kChat is a unified communication platform, where you can communicate live with your teams and organize projects in a secure and instant way, from the Swiss cloud provider Infomaniak.
Use the chat in the right bottom corner
