Support

Phones are rarely assembled perfectly square to their sensors. Put the phone on the flattest surface you have, open the bullseye level, tap Calibrate, then turn the phone 180° and tap again. Datum averages the two readings and stores the offset.

Android reports a nominal screen density that can be a few percent off. Open Ruler, tap "Calibrate with a card", lay a standard bank card (85.60 × 53.98 mm) on the outline and drag the slider until the edges meet. The correction is saved.

Check that Downbeat has the microphone permission in Android Settings → Apps → Downbeat → Permissions, and that no other app (a call, a voice recorder) is holding the microphone. The tuner only listens while its screen is open.

Yes. The reference pitch stepper on the tuner screen goes from 415 to 466 Hz in 1 Hz steps, and Downbeat remembers your choice.

Halloo listens from a foreground service with a notification, which Android normally keeps running with the screen off. Some phones still stop background apps aggressively: exempt Halloo from battery optimisation in Android Settings → Apps → Halloo: Clap to Find Phone → Battery. Halloo also stops by itself when its timer runs out, and if another app keeps the microphone for 10 minutes.

Startle watches from a foreground service with a notification, which Android normally keeps running with the screen off. Some phones still close background apps to save battery: exempt Startle from battery optimisation in Android Settings → Apps → Startle: Anti-Theft Alarm → Battery (the name differs by phone). Startle also stops by itself after the time you chose (30 minutes, 1 hour or 2 hours), and never arms itself again after the phone restarts.

To stop Startle, open Android Settings → Apps → Startle: Anti-Theft Alarm and tap Force stop. Anyone holding your phone can do the same, or switch the phone off. To remove the PIN, tap Storage → Clear storage there.

Relay keeps the screen on for the whole session. If the phone still stops it (for example after you lock the screen), some phones pause background apps aggressively: exempt Relay from battery optimisation in Android Settings → Apps → Relay → Battery.

In the EEA, the UK, Switzerland and US states with privacy laws, open the app’s Settings → Privacy → "Privacy options" to see the consent or opt-out form again. Everywhere, Settings → Privacy has a "Share usage statistics" switch, and you can reset or delete your advertising ID in your phone’s settings. See the privacy policy for details.

Yes. Every feature works offline. When a connection is available, the apps also use it for ads, the consent check, usage statistics, crash reports and to fetch app settings such as how often ads appear; none of that is needed for the tools to work.