What are some alternatives?
When comparing Ops Calender and Teamup Calendar, you can also consider the following products
Teamweek - A project management software to help you get the best overview. Plan fast, change plans faster!
Google Calendar - Spend less time managing your day & more time enjoying it
Time.ly - Time.ly is a collaborative calendar solution for websites.
Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
iCal - In Calendar on your Mac, subscribe to calendars published or shared by others.
CalendarX - Get a calendar your audience can follow