Real-Time Biofeedback.
Train Your Nervous System.
Respirix is a real-time HRV biofeedback app that uses chest-strap RR interval data to train your autonomic nervous system. Not a meditation app. Not camera-based estimation.
- Real-time heart rate + per-session RMSSD analysis
- Personalized resonance frequency testing
- Custom protocols, adaptive rate, and progress tracking
- No subscriptions
- No ads
- Works offline
A circle breathes with you
A visual pacer expands and contracts with each breath. Voice cues guide every inhale, hold, and exhale, even with the screen off. Add haptic feedback if you prefer to feel the rhythm instead of hearing it, or combine both.
Make it yours
Pair any Bluetooth HR chest strap for real-time HRV biofeedback, toggle voice cues and haptic feedback, enable adaptive breathing rate that adjusts to your coherence, and save sessions to Apple Health. Build custom breathing protocols with any combination of inhale, hold, and exhale durations. Everything is optional. Adjust as much or as little as you like.
Personalize your practice
Everyone has a breathing rate where heart rate variability peaks. That's your resonance frequency. A guided 10-minute assessment tests six different speeds and finds the one that maximizes your HRV. Or build your own protocols from scratch with any combination of inhale, hold, and exhale durations.
Track your progress
Every session is logged with duration, heart rate, RMSSD, and coherence metrics. Track your practice streak, view heart rate and HRV trends over weeks and months, and see how consistent breathing practice affects your autonomic regulation.
Who it's for
Built for
- Biohackers tracking autonomic nervous system regulation
- Athletes optimizing recovery through vagal tone training
- People with autonomic dysfunction seeking structured practice
- HRV enthusiasts who want real heart rate and RMSSD data
- Anyone wanting structured nervous system training
Not designed for
- People looking for a meditation app
- Casual relaxation timers
- Camera-based HRV estimation
This is not a meditation app.
How Respirix compares
| Feature | Respirix | Typical breathing app |
|---|---|---|
| Real RR interval data | ✓ | ✗ |
| Per-session RMSSD analysis | ✓ | ✗ |
| Resonance frequency test | ✓ | ✗ |
| Works offline | ✓ | Varies |
| Subscription required | ✗ | Usually |
| Bluetooth chest strap support | ✓ | Rare |
| Custom protocol builder | ✓ | Limited |
| Adaptive breathing rate | ✓ | ✗ |
Your data stays yours
All session data is stored locally on your device. Nothing is uploaded, shared, or sent anywhere. No accounts. No analytics. No third-party tracking.
Read our privacy policyFrequently asked questions
Do I need a chest strap to use Respirix?
No. Respirix works as a standalone breathing app with voice cues and a visual pacer. A Bluetooth chest strap unlocks biofeedback features: real-time heart rate display during sessions, plus per-session RMSSD analysis, coherence scoring, and the resonance frequency test.
What is RMSSD?
RMSSD (Root Mean Square of Successive Differences) is a time-domain measure of heart rate variability that reflects parasympathetic (vagal) activity. Higher RMSSD generally indicates stronger vagal tone. Respirix calculates RMSSD for every session and shows it in your session summary alongside heart rate and coherence data.
Is Respirix a medical device?
No. Respirix is a wellness and training tool, not a medical device. It does not provide medical advice, diagnosis, or treatment. The breathing protocols are informed by published research, but the app is not clinically certified.
Does Respirix work offline?
Yes. Respirix works completely offline. All data stays on your device. No accounts, no cloud sync, no internet connection required.
What chest straps are compatible?
Respirix works with any Bluetooth Low Energy chest strap that supports the standard Heart Rate Profile. This includes Polar H10, Polar H9, Garmin HRM-Pro Plus, Garmin HRM-Dual, Movesense, Wahoo Tickr, and many others. No proprietary hardware required.