Google Calendar - Spend less time managing your day & more time enjoying it
Cron - Cron Calendar.
Jorte - Schedule books must be practical and has a good design.
zcal - zcal is the fastest way to schedule every meeting for Free and make it personal.
Business Calendar - Powerful and easy to use calendar app for Android including weather, widgets and tasks.
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.