Many calendars use email to send reminders. Unfortunately, this can overshare data with mail servers & 3rd-party notification services.
At Tuta, we're doing something different. https://tuta.com/calendar
Our zero-knowledge calendar keeps you up to speed without sharing information with Google.
@Tutanota One thing I miss from Google calendar is where you can set a calendar event for the first (Day of Week) in a month. I'd like to have that in Tuta calendar too