Resonance

Privacy Policy

Last updated July 3, 2026

Resonance is a breathing-practice app with optional heart-rate-variability (HRV) biofeedback, made by David Presby. This policy covers the Resonance iOS app and the companion web app at davidpresby.com/apps/breathwork-hrv.

You can use the app fully without an account — your session data never leaves your device.
If you sign in, your session history syncs to a private backend so the iOS and web apps share one history. It is never sold, shared, or used for advertising.
You can delete your account and all synced data from inside the app at any time (Account → Delete account).

Data the app handles

On-device only (no account needed). Breathing-session records — start and end times, protocol, cycle counts, and, when a Bluetooth heart-rate sensor is connected, heart-rate and HRV metrics (heart rate, rMSSD, SDNN, coherence, spectral power) and R-R intervals. These are stored locally on your device and can be exported or cleared by you.

With an account (optional). If you create an account or sign in with Apple or Google, the app syncs the same session records to a Supabase backend project, associated with your account's email address and user ID. Sessions recorded without a live sensor never upload R-R interval data.

Not collected. No advertising identifiers, no location, no contacts, no tracking across other companies' apps or websites, no analytics SDKs in the iOS app. Bluetooth is used solely to read heart-rate data from a sensor you explicitly choose; the app never scans in the background.

How data is used

Synced data is used for exactly one purpose: showing you your own session history and trends across devices. It is not sold, shared with third parties, or used for advertising or marketing.

Storage and security

Synced data is stored with Supabase behind row-level security, so each account can only read and write its own rows. Your sign-in session on the device is stored in the iOS Keychain.

Deleting your data

Local data: clear history from the app's settings, or delete the app.
Account and synced data: Account → Delete account permanently removes your account, profile, and every synced session, sample, and R-R interval from the server. This cannot be undone.

Health disclaimer

Resonance supports general wellness and relaxation practice. It is not a medical device and does not diagnose, treat, cure, or prevent any condition.

Contact

Questions or data requests: david.m.presby@gmail.com