Privacy Policy

Birthday Sync for iPhone · Last updated October 27, 2026

Birthday Sync is made by Nathan Lewis. The short version: it collects nothing. Everything the app knows stays on your iPhone.

What the app uses, and where it stays

Contacts. With your permission, the app reads the names, birthdays, photos, phone numbers and email addresses in your contacts so it can show birthdays and address a birthday message. It writes to a contact only when you add or change a birthday yourself. This information is never sent anywhere, except birthdays you choose to share with a friend (below).

Your choices. Who you want reminders for, gift flags and reminder settings are stored in the app on your iPhone. Home Screen widgets read a copy stored on the same device.

Notifications. Reminders are scheduled on your iPhone. No push server is involved.

Messages. When you send a birthday message, iOS shows its own message screen and you choose whether to send it. The app never sends a message by itself and never sees your conversations.

Comparing with a friend. Only when you tap Share mine, the app makes a link (or, for a very long list, a file) holding the birthdays you picked. Each birthday is locked with a key made from that person’s phone number or email address; names, numbers and addresses aren’t in it. You send it yourself, with Messages, Mail or any app you like. The birthdays are in the part of the link after the “#”, which is never sent to a website, so birthdaysync.lewisapps.com only serves the page that opens the app and keeps no record of visits. Your friend’s phone can only unlock birthdays for people already in their own contacts. The lock makes guessing slow, but phone numbers are short, so someone with powerful computers could still work some out: share with people you trust. Changes you save from a friend’s share, and the birthdays from before, are kept on your iPhone so you can undo them in Past syncs.

What the app doesn't do

No account or sign-in. No analytics, advertising or tracking. No third-party SDKs that collect data. Nothing is uploaded to a server or sold, and nothing is shared unless you share it yourself.

Deleting your data

Settings › Restart setup › Erase everything removes everything the app has stored. Deleting the app also removes it. Your contacts are not affected either way.

Children

The app doesn't collect personal information from anyone, including children.

Changes and contact

If this policy changes, the new version will be posted here with a new date. Questions: create@nathanlewis.org.