This article documents basic and important information about external calendars:

  • The following calendars are supported by Calenso: Google Calendar, Apple iCloud, Microsoft Office365, Microsoft Exchange.
  • When a resource receives an online appointment booking from a customer, the appointment is synchronized to the calendar linked to the resource. At the same time, an appointment reference is generated in Calenso with a reference to the appointment in the external calendar.
  • If a customer cancels an appointment and this appointment is saved in an external calendar, the appointment and the appointment reference are deleted in Calenso.
  • For example, if a customer cancels the appointment by telephone, the partner must delete the appointment using the cancellation link or in Calenso. If only the appointment is deleted in the external calendar, a blocker still exists in Calenso. For this reason, the time window is not offered for further appointment bookings.
  • Calenso does not store appointments from external calendars on its servers. When calculating possible free appointments, Calenso only checks whether the times are "free" or "not available".


The following functions are planned for the future:

  • When a Calenso appointment is modified in a Google calendar or in an Office365 calendar, the appointment reference on the Calenso site should also be modified automatically (keyword "Webhook").
  • Support for iCal appointment feeds (e.g. calendar subscriptions)