Privacy

Last updated: 11 November 2026

What this policy covers

This policy covers Violin Metronome, an Android app published under the package name com.violinmetron.app by Hatsing.

The app has four tabs: Tuner, Metronome, Practice and Account. The tuner, the metronome and free-play practice work without signing in. Signing in is only needed to keep practice records and a membership across devices.

Microphone and audio

The tuner and the practice tab use the microphone to listen to your violin. Pitch, intonation and timing are calculated on the device.

During practice the app also keeps a short audio recording in its private storage so you can replay the session later. Recordings are never uploaded and are deleted when you delete the session, sign out of the device or uninstall the app.

Without microphone permission the tuner and practice tab cannot start listening. You can revoke the permission at any time in Android settings; the metronome and account pages keep working.

Practice records

Scores, per-note attack, sustain and release values, the intonation curve and session duration are stored on your device. If you are signed in they are also uploaded to our server so the same history appears on your other devices.

Practice records are used only to show your own history and statistics. We do not use them to train models, publish them or share them with third parties.

Accounts and sign-in

You can sign in with Google or Facebook. When you do, we receive an account identifier, a display name and an avatar URL from that provider, and an email address only if you grant it.

Your avatar is loaded from the provider's image servers when the Account page is shown, so those servers see the request.

This information is used only to identify your account, show your name and avatar, and determine membership status. We do not post on your behalf, read your friend list, use it for advertising or sell it.

Sign-in tokens are stored encrypted on the device. Signing out removes the token and ends the session.

Membership and payments

Subscriptions bought in the app are handled by Google Play. Payment, renewal, cancellation and refunds all happen in the Play Store, and we never see or store your card details.

Google Play gives us the product identifier, subscription state, expiry time and an anonymous account identifier. Our database keeps only the membership state, plan, expiry date and the purchase token needed to verify the subscription with Google.

If you subscribe on hatsing.com, payment is handled by our payment provider Creem and the app receives only the resulting membership state.

Analytics and diagnostics

The app uses Firebase Analytics (Google) to understand how features are used. It records app events such as screens opened, tuner and metronome settings, the sign-in method used, paywall views and completed purchases.

Each event is accompanied by app and device information such as app version, device model, operating system version, language, a randomly generated app instance identifier and, unless you opt out on the device, the Android advertising ID.

We use this data only in aggregate, to see which features are used and where the app fails. We do not use it for advertising, do not build advertising profiles and do not sell it. You can reset or delete the advertising ID in Android settings and turn off ads personalisation.

Google Play may additionally collect install, crash and ANR diagnostics under Google's own privacy terms.

What we do not collect

We do not collect your contacts, location, photos, files, health data or the content of your microphone input beyond the on-device analysis described above.

Retention and deletion

Practice records and recordings stay on the device until you delete them, sign out or uninstall the app. Server-side practice history is kept until you delete your account.

You can delete the account from the Account tab. Your name, email and avatar are cleared, every signed-in device is logged out and the account record is anonymised. Membership and Google Play records are kept only as long as needed to reconcile a subscription or meet tax rules.

If you have a Google Play subscription, cancel it in the Play Store first: deleting the app account does not cancel the subscription.

You can also ask us to delete the account by email: [email protected]. We reply within 30 days.

Who processes data

Google (Play Billing and Firebase Analytics), Meta (Facebook sign-in), Cloudflare (hosting and database) and Creem (web payments) process data on our behalf under their own terms and data processing agreements. We never sell personal data.

Your choices

Revoke the microphone or notification permission in Android settings at any time.

Reset or delete the advertising ID, or turn off ads personalisation, in Android settings.

Delete your account in the app or by email.

Ask us for a copy of your data or its deletion: [email protected].

Children

The app is not directed to children under 13 and we do not knowingly collect their data.

Changes and contact

If this policy changes we update the date above and, for material changes, show a notice in the app.

Privacy questions: [email protected].