If you have birthdays stored in your contacts and would like to see reminders in your calendar, then you can use this little form to convert your Google Contacts to a calendar ICS file.
How to use:
Go to your Google Contacts Page, click on the name icon/avatar on the left to check one, then on top select All or select your desired contacts.On top right with the 3 dots select Export and as format Google CSV as type and hit Export.
After converting you can simply create a new Google Calendar (or whatever Calendar you prefer) and import the generated birthday_calendar.ics file into it.
Due to changes in how Google Calendar handles Day-Long events, this converter will now create 2 events per birthday:
You can also now set the text reminder and select your timezone.
If you like, you can download this scripts source code here: index.php
Disclaimer: Your data is only stored for the convertion on the server, then immediately deleted.