A simple calendar with optional CalDAV synchronization. You can easily create recurring events and setup reminders, it can also display week numbers.

Contains a monthly view and an event list widget where you can customize the color of the text, as well as the alpha and the color of the background.

Contains no ads or unnecessary permissions. It is fully opensource, provides customizable colors.

The Storage permission is needed only for exporting or importing events from .ics files.

The Contacts permission is used only at importing contact birthdays and anniversaries.

This app is just one piece of a bigger series of apps. You can find the rest of them at www.simplemobiletools.com
From version Simple Calendar 4.0.4:
Make sure the alarm rings properly at DND mode
Improved the UK holidays and added Singapore ones
Make Event list items more compact when possible
Couple other UX improvements and bugfixes
All versions
June 3, 2018
May 23, 2018
May 15, 2018
May 12, 2018
April 13, 2018