What are some alternatives?
When comparing Ops Calender and ApPHP Calendar, you can also consider the following products
Teamup Calendar - Cloud-based calendaring using capability URL, application developed in Zurich, Switzerland.
Google Calendar - Spend less time managing your day & more time enjoying it
Teamweek - A project management software to help you get the best overview. Plan fast, change plans faster!
Time.ly - Time.ly is a collaborative calendar solution for websites.
Apple Calendar - Calendar is a personal calendar app made by Apple Inc. that runs on both the macOS desktop operating system and the iOS mobile operating system.
UpTo - Life goes beyond meetings and appointments