Resonance: HRV Biofeedback

Groma Apps

In-app purchases

About this app

Most breathing apps give you someone else's breathing rate. Resonance: HRV Biofeedback finds yours.

Your resonance frequency — the breathing pace that maximizes your heart rate variability (HRV) — is unique to you. It's usually 4.5 to 6.5 breaths per minute, but the exact rate is personal. Breathing there triggers respiratory sinus arrhythmia (RSA), strengthens vagal tone, and builds stress resilience. A generic pace like "6 breaths per minute" misses it for most people.

Resonance uses live HRV biofeedback to measure your actual resonance frequency, then trains you at that exact pace.

START WITH THE WATCH YOU ALREADY OWN

Turn on heart-rate broadcast on your Garmin, Polar, Samsung, or Fitbit watch and you're ready — no extra hardware to buy. Any Bluetooth chest strap or arm band works too (Polar H10, Garmin HRM-Pro, Wahoo TICKR, and more).

You only need a sensor twice: for the 12-minute assessment that finds your frequency, and whenever you want live coherence biofeedback. Every daily practice session after that runs at your stored pace with no sensor at all.

FIND YOUR FREQUENCY IN ABOUT 12 MINUTES

A three-phase protocol — ASSESS, REFINE, HOLD — scores candidate breathing rates against your live HRV using the published Shaffer et al. (2020) six-criteria coherence model, then locks in your personal resonance frequency and refines it each session.

LIVE HRV BIOFEEDBACK, NOT A BLACK BOX

• Real-time heart-rate trace and frequency spectrum during every session
• All six Shaffer coherence criteria live — peak LF power, single-peak dominance, LF concentration, peak height, SDNN, RMSSD
• Watch your heart rate turn into a smooth, sine-like wave as heart coherence builds

TRACK REAL IMPROVEMENT

• Session Quality Score (0–100) after every session — time in coherence, RSA amplitude, and consistency, scored separately
• Full session history with HRV trend charts for coherence, resonance, RMSSD, breathing pace, and heart rate
• Shareable session cards with your actual heart-rate trace

BUILT FOR DAILY PRACTICE

• A calm breath pacer with visual, audio, and haptic cues for eyes-closed sessions
• 10 sound packs and a breathing exercises library with multiple session modes
• Custom inhale/exhale ratio and practice reminders

PRIVATE BY DESIGN

Your heart-rate data never leaves your device. No account, no cloud, no sign-up. Everything works offline.

FREE TO START

The full resonance assessment and unlimited practice are free. Resonance Pro adds the adaptive pacer, full breath history, the complete resonance score, sound packs, and the exercises library — available monthly, annually, or as a one-time lifetime purchase.

THE SCIENCE

Built on 30+ years of peer-reviewed HRV biofeedback research. The engine uses Lomb-Scargle spectral analysis, the HeartMath coherence ratio, and the full Shaffer six-criteria model — the same methods used in clinical biofeedback, computed on-device.

Resonance: HRV Biofeedback is a wellness tool, not a medical device; it does not diagnose or treat any condition.

References:
Task Force (1996)
Lehrer et al. (2000)
Shaffer & Ginsberg (2017)
Shaffer et al. (2020)

COMPATIBLE DEVICES

Any Bluetooth 4.0+ heart-rate sensor using the standard Heart Rate Service — smartwatches, chest straps, and arm bands. Tested with Garmin HRM-Pro, Polar H10, Wahoo TICKR, and Garmin, Polar, Samsung, and Amazfit watches with heart-rate broadcast on.

WHO IT'S FOR

Anyone training heart coherence and resonance frequency breathing — for stress, anxiety, focus, sleep, and vagal tone. First-timers who want a guided daily practice that works, athletes using breathwork to recover and downregulate, and researchers who want live spectral analysis, RMSSD, SDNN, and raw R-R export. No prior HRV knowledge needed.

Resonance frequency breathing. HRV biofeedback. Heart coherence training. Vagus nerve activation. Measured, not guessed.

Ratings and reviews

Amazing! Free, no ads and works flawlessly. You can test to find your resonant breathing frequency and you can allow it to make adjustments over multiple practice sessions. Oh, and you can turn on haptic feedback so that you can close your eyes and focus on deep meditation. Highly recommended!

After years of looking for a good hrv biofeedback app, and using several different ones, I've finally found one that gives me exactly what i was looking for. I also really appreciate that it has no ads.

Incredible tool for mastering resonance breathing If you're looking to practice resonance breathing, this app is a total game-changer. Most breathwork apps just give you a generic, static timer, but Resonance:HRV Feedback actually uses real-time biofeedback to help you find your exact personal breathing sweet spot (your resonance frequency). ​The visual guides make it incredibly easy to sync your breath with your heart rate. There's zero guesswork—you can literally watch your nervous system shi

What’s new

Fixed the breath ball jumping to a different point in its cycle after resuming a paused session — it now picks up exactly where it left off.

Sessions stopped before one minute are no longer saved to history.

Practice reminders are now free for everyone, and the app offers to set one up after your first practice session.


Practice sessions now end with a short reflection — a quote on stillness and awareness drawn from classic sources.