Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
24me - Next Generation Personal Assistant
Google Calendar - Spend less time managing your day & more time enjoying it
WeekCalendar - WeekCalendar is an all-in-one calendar application designed to provide everyone with all the features they need to work to their fullest.
Itsycal - Itsycal for Mac. Itsycal is a tiny menu bar calendar. If you want, it will display your events as a companion to the Mac Calendar app. You can also create and delete (but not edit) events. Download Itsycal for macOS 10.
Calvetica - The fast calendar for iPhone. Add an event in just two quick taps.