Microsoft Office Outlook, Google Calendar, Fantastical, Notion Calendar, Apple Calendar, DigiCal, Lightning Calendar, Amie, Teamup Calendar, HEY Calendar, Sunsama, CalenGoo, Sunrise Calendar, WebCalendar, Sol: Sun Clock, Appoint.ly, MeetingBar, WAVE Calendar, GCalToolKit, CalendarWiz, MeetVibe, Easy Event, Merge Calendar are some alternatives to Cron Calendar.