Google Calendar - Spend less time managing your day & more time enjoying it
BusyCal - powerful calendar app for macOS
Jorte - Schedule books must be practical and has a good design.
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.
Business Calendar - Powerful and easy to use calendar app for Android including weather, widgets and tasks.
Calendar Widget: Month - Calendar Widget: Month is a significant calendar app developed and published by Candi Apps.