📅 iCalendar

iCalendar (often shown as .ics) is a universal calendar format supported by major platforms like Google Calendar, Outlook, iCloud, Airbnb, and many more.
It allows you to sync bookings or events with your calendar apps, so you never miss a reservation.

Google Calendar

https://support.google.com/calendar/answer/37100 

Microsoft Outlook

https://support.microsoft.com/en-us/office/import-or-subscribe-to-a-calendar-in-outlook-com-or-outlook-on-the-web-cff1429c-5af6-41ec-a5b4-74f2c278e98c

https://support.apple.com/en-us/102301

Airbnb 

https://www.airbnb.com/help/article/99

Booking.com

https://partner.booking.com/en-us/help/rates-availability/extranet-calendar/syncing-your-bookingcom-calendar-third-party-calendars