StopSure — Privacy Policy

Effective date: November 1, 2026

StopSure ("the App") is a stop alarm for subway and light-rail trains, developed and operated by an independent developer. This policy explains what data the App uses, where it goes, and your choices.

In Short

Audio and trips never leave your phone. The App listens only while you're on a train, processes the sound on your phone as it comes in, and never saves or uploads it. Your stations and your rides stay on your phone. The App sends only anonymous usage statistics, which say at most which city you chose — never your stations, lines, or when you ride.

Microphone

The App uses the microphone to hear the station announcements on the train, which is how it knows where the train is.

• It listens only during a ride: once the App has decided you're on a train (or you tapped its banner when boarding), until the ride ends.
• The sound is processed in real time by speech-recognition models that run on your phone. It is never recorded to a file, stored, or sent anywhere.
• While StopSure is on and set to start automatically, Android shows that the App may use the microphone; it does not listen while you're not on a train.

Motion Sensors

The App reads the accelerometer, magnetometer and barometer to tell when you're on a train and when you get up and walk, and the proximity sensor to ignore taps from inside a pocket or bag. Sensor readings are processed in real time and never stored or sent.

What Stays on Your Phone

• Your settings: your city, the stations you saved, and the App's two switches.
• A short ride count: the times you started a ride in the last 7 days, used only to count rides for the weekly statistic below.
• A diagnostic log (at most about 1 MB, older lines removed first): what the App did and when — for example, which station names it heard and which alerts it showed. It never contains audio. It stays on your phone and leaves it only if you choose to share it with us, for example to report a problem.

You can erase all of this at any time by clearing the App's data or uninstalling it.

Android backup: if backup is on for your phone, Android may include your settings (city and stations) in your phone's backup in your Google account, or copy them to a new phone. The diagnostic log, ride count and statistics are excluded from backup.

Anonymous Usage Statistics

The App uses Google Analytics for Firebase (a service of Google LLC) to count how the App is working across different phones — for example, that a ride started, that an alert was shown and answered, or that a permission was granted. Alongside each event, Google's SDK records general device information: device model, operating-system version, app version, a randomly generated app-instance identifier, and an approximate location that Google derives from the network address (country, region or city).

• Never included: station names, lines, any place below the city you chose, the times you ride, or any audio. Values like ride length or how long an alert took to be answered are sent only in coarse ranges.
• Included: the city you chose and whether the App starts automatically, as properties of your anonymous identifier.
• Sent once a day: the App queues its events on your phone and sends them together, so they don't carry the times of your rides.
• Google's SDK also records when the App's screens are open (session start and engagement time). This can include the alert screen, so it may show roughly when the App was in use.
• Google's SDK may also note where the App was installed from (Google Play's install referrer, for example a store link).
• No Advertising ID: the App disables Advertising-ID collection, removes the advertising-ID permissions (including Android's Ad Services ones) and turns off ad-personalisation signals.
• No name, email, account, GPS location or contacts — the App never asks for any of these.
• Data is encrypted in transit and retained by Google Analytics for up to 14 months, then deleted automatically. Uninstalling the App (or clearing its data) resets the random identifier.

For how Google processes this data, see Google's Privacy Policy.

Earbud Voice

With earbuds connected (and the earbud voice switch on), the App says the station name using your phone's own text-to-speech engine, with an offline voice only. Nothing is sent anywhere.

Permissions

• Microphone — to hear station announcements during a ride, as described above.
• Display over other apps (also called "Appear on top") — to show the alert and the boarding banner over whatever is on screen, and the alert card over the lock screen.
• Foreground service — keeps StopSure ready between rides. Android requires a low-priority notification for this; the App does not ask for permission to send notifications.
• Run in the background (battery optimization) — optional; lets the App keep running reliably. Grants no access to any data.
• Start at boot, vibrate, keep awake — to be ready again after a restart, to vibrate for an alert, and to keep the alert going until you answer it.
• Internet — only to send the anonymous usage statistics. The speech models are delivered by Google Play.

No location, camera, contacts, Bluetooth or notification permissions are requested.

Third-Party Services

The App contains no advertising or ad-tracking SDKs. The only third-party service is Google Analytics for Firebase, used solely for the anonymous usage statistics described above, with Advertising-ID collection disabled.

Data Sharing

We do not sell or share your data. The anonymous usage statistics are processed by Google on our behalf as a service provider; no other party receives any data.

Your Choices

• Turn off "Start automatically on trains" and the App uses the microphone only after you tap its banner when you board.
• Turn StopSure off in the App at any time; it then stops watching for trains and uses no sensors or microphone.
• Revoke any permission in your phone's settings, or clear the App's data, or uninstall it.

Children's Privacy

The App is not directed at children under 13. We do not knowingly collect information from children.

Changes to This Policy

If we update this policy, the revised version will be posted on this page with a new effective date.

Contact

If you have questions about this policy, contact us at support@stopsure.app.

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