Germany
Nextcloud is the open-source engine that many of the other services on this page quietly run on, including Office.eu and Murena. Started in 2016 by Frank Karlitschek in Germany, it gives you files, calendar, contacts, real-time document editing and the Talk app for chat and video calls, all in one place.
You can install it on your own server if you have the skills in-house, or pay a European hosting provider to run and maintain it for you. Because the code is open and your data stays in formats you control, it is the option best suited to teams and public bodies that want to own their whole stack rather than rent it from a US vendor.
