Awesome Cal - Awesome Cal is a Calendar application for your iPhone that you can take anywhere and keep close by to monitor all the upcoming birthdays, festivities, meetings, and more from a single place.
FamCal - FamCal is an organized and managed calendar to track the family records like events, notes, and dates of births.
Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
Sectograph - Sectograph app enables you to create a visual event tracker to keep track of all your upcoming events and due tasks right from the home screen.
Pocket Informant - Pocket Informant is the Best Calendar app for mac and iOS. Pocket Informant for iOS, Mac desktop, and Android.
Power Planner - Record homework and class schedule.