What are some alternatives?
When comparing Simple Calendar and Lightning Calendar, you can also consider the following products
Google Calendar - Spend less time managing your day & more time enjoying it
MineTime - MineTime is a free, modern and multi-platform calendar application.
Rainlendar - Rainlendar - Customizable desktop calendar
Apple Mail - There’s big news attached.
Etar - Material design open source calendar for Android.
Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.