What is the closest alternative to Outlook calendar for scheduling?

Question

Calendar

For joint scheduling of events in a common calendar with notification of participants, there is a Microsoft Outlook + Exchange solution. In terms of one user, a rather expensive license is obtained.

Can anyone suggest a similar solution?
You need to plan events in a common calendar with the ability to notify event participants by mail

Answer 1

https://support.google.com/a/answer/1626902?hl=en
but there is also $ 5 for each, the
alternative is self-written software with soaps, and Google accounts of each will add to the calendar themselves