When Was It application. A birthday and anniversary reminder application with several nice functionalities:
- Multiple notifications in advance
- Support for anniversaries as well as birthdays
- Automatic daily import
- Different colors depending on how close the anniversary is
- No issues with huge number of contacts
- Ability to show the age the contact will have at the end of this year
- Improved date handing (no longer says wrong age or days to birthday)
- No longer creates duplicate accounts by accident
- Show contact pictures, if available
- Works on Android Pie
- Other improvements

Suggested usage:
Although you can add the birthday details directly in the app it's better to add the details directly to the Google contact and let the application automatically synchronize - that way you have the birthday information on all your devices and if you reinstall your phone or the app you will automatically have all the birthdays and anniversaries again.