Birthday Sync
Birthday Sync
Your contacts’ birthdays in your calendar. Automatic, private, no internet access.
A free Android app that writes the birthdays from your contacts as real events into the calendar you choose – for example your Google calendar – keeps them up to date and reminds you on the day.
Why Birthday Sync?
Since 2024, Google Calendar no longer reliably shows your contacts’ birthdays for many users in Germany and the EU – Google cites an agreement with a German regulator. The birthdays are still in your contacts; Birthday Sync turns them into calendar events that you control.
| Feature | Birthday Adapter | Birthday Sync |
|---|---|---|
| Birthdays from your contacts in a calendar | yes | yes |
| Write into any calendar, e.g. your Google calendar (visible on the web and other devices) | no | yes |
| Daily notification listing today’s birthdays | no | yes |
| Free and open source | yes | yes |
Birthday Adapter (F-Droid) provides its own local birthday calendar and is a good choice if that is all you need.
Set it up once, then forget about it
Birthday Sync runs in the background and keeps your calendar in step with your contacts.
Your choice of contacts
Whole contact accounts – Google, device, Exchange and others – or individual groups and labels.
Any calendar
Write into any writable calendar on the phone, or let the app create a local “Birthdays” calendar.
Events your way
All-day or at a set time with a duration, an optional reminder, and a title template like 🎂 {name} ({age}).
Always up to date
Daily or weekly sync, 1–12 months ahead. Changed birth dates are updated, removed contacts disappear.
Daily notification
At a time you choose, only on days when someone has a birthday – straight from your contacts.
Guided setup
Each permission is asked on its own screen with an explanation. The System tab checks battery optimization, background limits and app hibernation.
40 languages
From Arabic to Vietnamese, with per-app language selection on Android 13 and later.
No internet access
The app has no internet permission, no ads and no tracking. See the privacy policy.
Free and open source
MIT License. Read the code, report issues, help with translations.
Screenshots will follow.
How it works
Every event Birthday Sync creates carries a small marker at the end of its description, #birthday-sync key=… v=…. The app only ever touches events with this marker – your other appointments stay as they are. It needs no database of its own and finds its events again even after a reinstall.
- Name, title template, time or reminder changed → the event is updated.
- Birth date changed, contact removed or deselected → the event is removed (and re-created on the new date).
- Target calendar changed → the events move to the new calendar.
- Past events are left alone.
Install
- Download
BirthdaySync-<version>.apkfrom the latest release on your phone. - Open the file. Android asks once whether your browser or file manager may install apps.
- Start Birthday Sync and follow the setup: choose contacts, choose a calendar, done.
FAQ
Is Birthday Sync really free?
Yes. It is open source under the MIT License, with no ads, no in-app purchases and no account.
Does Birthday Sync connect to the internet?
No. The app has no internet permission and makes no network connections at all – no analytics, no crash reporter. Your contacts and calendar stay on your device. Details in the privacy policy.
Will the birthdays show up on my computer, too?
Yes, if you choose a synced calendar such as your Google calendar as the target: your calendar provider syncs the events like any other appointment. The local “Birthdays” calendar stays on the phone only.
Does the app change my contacts or other appointments?
No. Contacts are only read. In the calendar, Birthday Sync only creates, updates and deletes its own birthday events, recognised by the marker in their description.
I see some birthdays twice.
If your calendar app still shows its own birthday calendar, hide that one in the calendar app’s settings.
The sync or the notification doesn’t run in the background.
Open the System tab in the app: it checks battery optimization, background restrictions, app hibernation and exact alarms, and shows hints for manufacturers that stop background apps.
What happens when I uninstall the app?
The events stay in your calendar. To remove them, use Calendar → Remove events in the app before uninstalling.
Which Android versions are supported?
Android 8.0 (Oreo) and later.
How can I help?
Report bugs, suggest features or review a translation – many languages were translated with the help of AI. See CONTRIBUTING.md.