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Birthday Sync

Puts the birthdays from your Android contacts into the calendar you actually use – automatically, on your device, without internet access.

Status: 0.1.0 is the first public release. See the changelog and the roadmap. Screenshots will follow.

Why Birthday Sync?

For years, Google Calendar showed your contacts' birthdays automatically. Since 2024 this no longer works reliably for many users in Germany and the EU – Google cites an agreement with a German regulator. The birthdays are still in your contacts, they just don't show up in the calendar any more.

Birthday Sync writes real calendar events for these birthdays into a calendar you choose – for example your Google calendar, so they also appear on the web and on your other devices – and keeps them up to date. You decide which contacts are included, how the events look and whether you get a reminder. On top of that, it can send a daily notification listing today's birthdays.

Birthday Adapter (F-Droid) is a good choice if a separate local birthday calendar is all you need. Birthday Sync can write into any calendar on the device, including synced accounts, and adds the daily notification.

Features

• Choose your contacts – whole contact accounts (Google, device, Exchange and others) or individual groups/labels.
• Choose your calendar – any writable calendar on the device, or a local “Birthdays” calendar that the app creates for you.
• Events your way – all-day or at a set time with a duration, an optional calendar reminder, and a title template with {name} and {age} (default: 🎂 {name} ({age})).
• Automatic sync – daily or weekly in the background (WorkManager), 1–12 months ahead.
• Keeps the calendar in step – changed names or birth dates update the events; removed or deselected contacts disappear from the calendar.
• Daily notification – at a time you choose, only on days when someone has a birthday, straight from your contacts.
• Guided setup – asks for each permission on its own screen and explains why it is needed.
• System checks – battery optimization, background restrictions, app hibernation, exact alarms, Battery Saver and hints for manufacturers known to stop background apps.
• 40 languages – with per-app language selection on Android 13+.
• Private – no internet permission, no ads, no tracking, no analytics, no account.
• Free and open source – MIT License.

How the sync works

Every event that Birthday Sync creates carries a marker at the end of its description: #birthday-sync key=<contact>_<date> v=<version>. The app only ever changes events with this marker, and it needs no database of its own – it finds its events again even after a reinstall.

• Name, title template, time or reminder changed → the version differs → the event is updated.
• Birth date changed, contact deleted or deselected, range shortened → the event is removed (and re-created where needed).
• Target calendar changed → the events move to the new calendar.
• Past events are left alone. Future events you delete by hand are created again by the next sync.
• Calendar → Remove events deletes all events created by Birthday Sync from all calendars.

Install

Requirements: Android 8.0 (API 26) or later.

• APK from GitHub: download BirthdaySync-<version>.apk from the latest release and open it on your phone. Android asks you once to allow installing apps from your browser or file manager.
• Obtainium: add https://github.com/brokoskokoli/birthday-sync in Obtainium to install the release APK and get updates directly from GitHub.
• Google Play, IzzyOnDroid / F-Droid: planned.

Updates are installed the same way; your settings are kept. The debug build from source is signed with a different key and cannot be installed over a release.

Verify the download

Release APKs are signed with the project's release key. You can check the signature with apksigner verify --print-certs BirthdaySync-<version>.apk (Android SDK build tools) or in AppVerifier. The SHA-256 fingerprint of the signing certificate is:

98:3B:31:F1:02:F0:75:7F:5F:27:88:A3:10:88:DF:A1:DF:60:97:18:8E:84:00:94:56:37:75:AF:83:DA:CB:40

Quick start

1. Open Birthday Sync. The setup asks for each permission and explains what it is for; you can skip steps and complete them later in the System tab.
2. Contacts: choose the accounts or groups whose birthdays should be included.
3. Calendar: choose the target calendar (or create the local “Birthdays” calendar), all-day or timed, reminder, title and sync range.
4. Overview: tap Sync now – from then on the app syncs automatically.
5. Alerts: turn on the daily notification and pick a time.

If the sync or the notification doesn't run in the background, check the System tab: some manufacturers stop background apps unless you allow it explicitly.

Build from source

Requirements: JDK 17 or later (the JetBrains Runtime bundled with Android Studio works) and the Android SDK (API 36).

# macOS with Android Studio's JDK (adjust the path on other systems)
export JAVA_HOME="/Applications/Android Studio.app/Contents/jbr/Contents/Home"

./gradlew assembleDebug                 # app/build/outputs/apk/debug/app-debug.apk
./gradlew testDebugUnitTest lintDebug   # unit tests and lint

./gradlew assembleRelease signs the release APK only if a signing configuration exists: either signing/keystore.properties (keys storeFile, storePassword, keyAlias, keyPassword; not in the repository) or the environment variables SIGNING_STORE_FILE, SIGNING_STORE_PASSWORD, SIGNING_KEY_ALIAS and SIGNING_KEY_PASSWORD. Without them the release APK is unsigned.

Privacy

Birthday Sync has no internet permission and makes no network connections at all. It reads names, birthdays and account/group membership from your contacts and reads and writes calendar events – only on your device, and it only ever changes its own birthday events. Settings are stored locally. There are no ads, no analytics and no tracking. Tapping Privacy or Source code in the app opens your browser. Details: privacy policy.

Roadmap

• 0.1.0 – first public release (APK on GitHub)
• Screenshots
• Google Play
• IzzyOnDroid / F-Droid
• Reviewed translations

Ideas and votes are welcome in Discussions.

Translations

The app and its store texts are available in 40 languages. Apart from English and German, many translations were made with the help of AI. If you are a native speaker, please help review them – the texts are in app/src/main/res/values-<lang>/strings.xml and fastlane/metadata/android/<locale>/. Open a translation issue or a pull request; see CONTRIBUTING.md.

Contributing

Bug reports, ideas, translations and pull requests are welcome. Please read CONTRIBUTING.md first. This project follows the Code of Conduct. Report security issues privately as described in SECURITY.md.

License

Birthday Sync is free software under the MIT License; see LICENSE. The repository follows the REUSE specification (REUSE.toml); the Gradle wrapper is Apache-2.0, the Code of Conduct CC-BY-4.0.

Acknowledgements

Built with Kotlin, Jetpack Compose, Material 3 and WorkManager (Apache-2.0).