Calenso is hosted in Switzerland at nine.

nine is the leading provider of managed service solutions in Switzerland and offers full platform management in the public cloud and the private cloud, both of which use the Swiss site. The company is ISO 27001 and ISO 9001 certified and employs around 40 people. Operations are guaranteed at three data centre locations. nine stands for maximum availability, highest performance, 24/7 monitoring and full scalability. nine is fully compliant with DSGVO.

This means that Calenso's data is only ever stored and archived in Switzerland.