How are there open source corporate projects for hosting web calendars on an Intranet?

Question

Calendar

Good afternoon, I'm looking for some kind of tool with which you can raise a certain service / server for organizing web calendars on the network (Intranet)
. to be able to integrate with Active Directory, differentiation of rights, etc.
In other words, any user could log in and create calendar entries for himself, as well as create some meetings with participants, and integrate with other services and display their information in the calendar
. Is there any solution?
Intranet without Internet access

Answer 1

It all depends on the size of the company. What works for the little ones may not work for the big ones. For large zimbra, for small zarafa and a bunch more. Turn on the internet. However, as a rule, calendars are not made separately, because they are still tied to mail, a catalog and other means.

Answer 2

zimbra, zarafa, horde, SoGo. True, these are not separate calendar servers, but Groupware servers - mail, calendar, contacts, tasks, notes - Exchange for Linux and not only...