Stretch: Piano Tuner Pro

This privacy policy applies to the Stretch app (the "Application") for iOS on iPhone and iPad, created by Cihat SALIK (the "Service Provider"). The Application is offered as a service and is intended for use "AS IS".

Stretch is an electronic tuning device for pianos. It measures the inharmonicity of an instrument through the microphone, calculates a tuning for all 88 keys, and keeps a file for each piano you work on. All of that happens on your device.

The microphone is used only while you are measuring or tuning. The incoming audio is analysed in real time to detect pitch and the partial frequencies of the note being played. The audio itself is never recorded to a file, never stored and never transmitted — only the numbers derived from it (frequencies, cents deviation, inharmonicity coefficients and a confidence value) are kept, and only as part of the piano you are working on.

Deny the microphone permission and the Application cannot measure or tune; nothing else about it changes.

A piano file holds what you enter and what the Application measures: client name, make, model, serial number, location, your notes, the last tuning date, the measured inharmonicity curve and before and after deviation snapshots. Sessions, temperament and stretch settings and your app preferences are stored alongside it.

This data is stored on your device with SwiftData. It is not uploaded to the Service Provider's servers or to any third-party service, and there is no account, so the Service Provider cannot see, retrieve or delete any of it.

You are responsible for the personal data of your clients that you choose to enter. Only enter what you need, and tell your clients what you keep if the law where you work requires it.

iCloud sync keeps your pianos and sessions on all the devices signed in to your Apple Account, through Apple's private CloudKit database. The data travels between your devices and Apple only; the Service Provider operates no server and has no access to it. Turn sync off in Settings and the Application returns to a store that never leaves the device.

A before and after report is rendered on the device as a PDF and handed to the iOS share sheet. Where that PDF goes — mail, messages, a file, a printer — is your choice, and nothing is sent anywhere until you choose a destination.

The Application contains no analytics or tracking SDK, no crash reporting service and no advertising, and it requires no account. It makes no network requests of its own: the only traffic it causes goes through Apple's StoreKit for purchases and restores, and through Apple's CloudKit if you turn iCloud sync on.

If analytics or similar tools are added in a future version, this policy will be updated to describe them before that version ships.

Stretch is free to download and to use for checking and touching up a piano. Home Plus is a one-time purchase, and Pro is offered as a one-time unlock or as an annual subscription with a free trial. Payments are processed by Apple through the App Store. The Service Provider does not receive or store your payment card details. Apple's handling of purchases, renewals and restores is governed by Apple's own terms and privacy practices.

Because the data is on your device, you control it directly. Delete a piano and its file, curve and history go with it. Deleting the Application removes its data from the device; if iCloud sync was on, deleting a record inside the Application also removes it from iCloud.

The Service Provider does not knowingly collect personal information from children under 13 through Stretch. The Application stores everything on the device, requires no account and sends nothing to the Service Provider.

If you believe information was collected from a child inappropriately, contact the Service Provider at cihatsalik1@gmail.com.

The security of your on-device pianos and client files depends on your device passcode and biometric settings. The Service Provider recommends keeping iOS up to date and using the device security features offered by Apple.

This Privacy Policy may be updated from time to time. Material changes will be reflected by updating this page and the "Last updated" information where shown. Continued use of the Application after changes constitutes acceptance of the updated policy.

If you have questions about this Privacy Policy or Stretch, contact the Service Provider at cihatsalik1@gmail.com.