Privacy policy
Last updated October 26, 2026
Treadwell measures your treadmill's real belt speed using your iPhone's camera and LiDAR sensor. This policy explains what the app collects, what it doesn't, and what happens to your data. The short version: almost everything stays on your phone. The app shares anonymous usage counts unless you turn that off in Settings, and it sends a video clip only if you say yes.
What stays on your phone
- The measurement itself. The app uses your camera and LiDAR sensor to watch the belt and calculate its speed. That video and the calculation happen on your phone. They are not uploaded anywhere by default.
- Your calibrations, treadmills, runs, and settings. Calibration profiles, saved treadmills, workout and run history, and app settings are stored locally on your device. They are not sent to a server.
- Apple Health and Apple Watch. Heart rate and cadence from your Apple Watch, and anything Treadwell reads from or writes to Apple Health, stay on your devices. Treadwell never sends Health data or watch motion data to us or to anyone else. The anonymous usage counts below do include a finished run's distance and time as Treadwell measured them.
- An install identifier. On first launch the app generates a random identifier and stores it on your device. It is not derived from any hardware identifier and carries no personal information by itself. It exists so we can tell one phone's usage counts, reports, and clips apart from another's. Only the first 8 characters are ever sent.
What the app does not collect
- No location data of any kind. No GPS, no network names.
- No contacts, no photo library access, no microphone recording.
- No advertising identifiers and no third-party analytics or advertising SDKs.
Purchases
The one-time Pro unlock is handled entirely by Apple's App Store. Treadwell never sees or stores your payment details; Apple processes the transaction.
Problem reports you choose to send
After a failed measurement, or from Settings with "Report a problem", you can choose to send us a report. It contains a short video clip of the treadmill belt (your feet may appear if they were in view), tracking data, device diagnostics, and a log of recent app activity for up to your 5 most recent measurements, plus a name, email, and note if you choose to add them. It goes only to the developer's private storage, is used only to fix tracking problems and to train the app's own belt reader, and is not shared with anyone else. Nothing is sent unless you tap the button.
Help improve Treadwell
Two settings, both under Settings, "Help improve Treadwell". You can change either one at any time.
- Share anonymous usage (on unless you turn it off). The app sends simple counts so we can see which parts of Treadwell work and where people get stuck. It is on when you install the app, and the first time you open it a short notice says so, with a button to the off switch. If you turned sharing down in an earlier version ("Not now"), it stays off. The counts cover:
- when the app was opened and how long it stayed open, and which tabs and screens you used;
- whether you finished or skipped the first-time guide;
- whether each reading worked or failed and why, the screen it came from, your speed rounded to a tenth of a mile per hour, which on-screen warnings appeared, and whether the phone looked to be over the belt or behind it; a refused reading can carry a few speed and motion numbers that tell us why it was refused;
- calibration started and finished, with its accuracy;
- the treadmill speed you entered to compare against, the difference shown, and whether you tapped to calibrate;
- upgrade steps: when the upgrade screen was shown, and whether a purchase or restore was tapped, finished, was cancelled, or failed, and the same for the free trial, plus whether the app is free, in its free trial, or unlocked (Apple handles the payment; see Purchases above);
- runs started, with their starting speed, and finished, with their distance and time;
- whether you opened the share screen, where you shared to, such as Messages or Instagram Stories, and which kind of card it was, never the image itself.
Each line also carries your iPhone model, iOS version, app version, and the short install identifier above. There is no video, no location, no name, no email, no heart rate or other Health data, and no text you type. Counts are sent when you leave the app. Turning this off stops collection at once and deletes anything not yet sent.
- Always send failed clips (off until you say yes). When a reading fails, the app can send that clip so we can fix it for your treadmill. The first time a reading fails, the app asks once whether you want this. A clip is a short video of the belt (your feet may appear if they were in view) with the tracking data, device diagnostics (including how the phone was tilted and moved while measuring), a log of recent app activity, and the same short install identifier. It carries no name, email, or note. Automatic clips send only on Wi-Fi, never on cellular, and the copy on your phone is deleted once it has been received. If you instead tap "Send this clip" on a failed reading, that clip sends right away on whatever connection you have. Clips go only to the developer's private storage, are used only to fix tracking and to train the app's own belt reader, and are not shared with anyone else.
Because usage counts and clips carry no name or email, we generally can't tell which ones came from you. Turning the settings off is how you stop them.
If you're a beta tester (TestFlight)
TestFlight beta builds work differently from the public App Store version:
- Beta usage stats. Beta builds automatically record when the app is opened and which features are used, along with the device model, iOS version, and app version, tied to the install identifier above and to the tester name you gave us. This helps us understand what beta testers actually use. The public App Store version sends only the anonymous usage counts described above, which carry no name and which you can turn off.
The website
This website (treadwellapp.com), separate from the app, uses Microsoft Clarity to record anonymized page activity, such as which pages are visited and how far down them people scroll, so we can improve the site. The site has one optional form, at treadwellapp.com/phones, where you can tell us which iPhone you have and, if you like, leave an email so we can let you know when Treadwell works on your phone. That form is held by our website host, Netlify, and used only for that. If you joined our email list while Treadwell was in beta, that address is held with our email provider, MailerLite, and used only to contact you about Treadwell. None of this has anything to do with the app on your phone.
Deleting your data
Because your data lives on your device, deleting the app removes it. Anonymous usage counts and clips already sent can't be matched to you, as described above. If you sent us a report with your name or email, or your email is on our list or our phone form, contact us at support@treadwellapp.com and we'll delete what we hold.
Children
Treadwell is not intended for use by children under 13.
Changes
If a future version of the app changes what it collects, this policy will be updated before that version ships, with the date above.
Contact
Questions about this policy: support@treadwellapp.com