Privacy Policy

Stack for iPhone and Mac · Last updated 4 November 2026

Stack does not collect any data. There is no account, no server, no analytics and no advertising. Everything Stack works with stays on your own devices.

What Stack reads, and where it stays

Head motion from your AirPods (through Apple's Motion & Fitness permission). Stack uses the angle of your head to notice when you have been looking down for a while. The readings are processed on your iPhone or Mac and are not sent anywhere.
Motion activity (walking). Used only to hold nudges back while you walk. It stays on your iPhone.
The front camera, during neck stretches only. Apple's on-device face tracking gives Stack the position and angles of your head so it can count each move. Camera images are never stored, shown or sent anywhere.
Your posture history (how much of each day you sat upright) and your settings. These are kept on your device. They are deleted when you delete the app.

Notifications

Nudges are local notifications created on your iPhone or Mac. They are not sent through any server. iOS may show them on your Apple Watch, as it does for any app.

Stack for Mac and your iPhone

If you use Stack for Mac, it finds Stack on your iPhone over your local network or a direct peer-to-peer connection (the Local Network permission) and sends it a short message such as "nudge". Nothing goes over the internet and nothing is stored by anyone else.

Third parties

Stack contains no third-party analytics, advertising or tracking code, and shares no data with anyone. Apple processes App Store purchases and downloads under Apple's own privacy policy.

Children

Stack does not knowingly collect information from anyone, including children, because it collects no information at all.

Health

Stack is a wellness reminder, not a medical device. It does not diagnose or treat any condition.

Changes

If this policy ever changes, the new version will be posted on this page with a new date. Stack will not start collecting data without asking you first.

Contact

Questions: safelibrahim@gmail.com