Is there any kind of calendar service that my department can use without signing up for any service (such as Google or Microsoft), i.e. you only need the calendar link and then you can edit freely from inside your own calendar application (such as Apple Calendar or Outlook). People around here use their department emails, Gmails, Outlook and a lot of scattered services, and are not keen on tech/adapting. I found a service called Teamup Calendar which is almost what I want. It's possible to subscribe to the calendar for everybody, however, events can only be edited from the web interface. Any ideas?