Nostril
Your breathing coach, powered by machine learning. Nostril uses three layers of on-device ML to track your breathing while you sleep, measure your breathing fitness, and help you switch to nasal breathing for good. Every bit of processing happens on your phone.
You breathe 20,000 times a day
01Most of them through your mouth, without knowing it. Mouth breathing causes poor sleep, low energy, dry mouth, snoring, and anxiety. Nostril proves it with data and helps you fix it with science.
Every screen
From overnight tracking to daily check-ins.02
Not another meditation app
Real machine learning, real breathing science.03Three-layer ML fusion
YAMNet deep learning, Apple SoundAnalysis, and custom FFT spectral analysis work together to classify every 5-second audio window while you sleep.
Sleep breathing tracker
Place your phone on the nightstand. Wake up to a full report: nasal vs mouth breathing percentage, snoring episodes, intensity, and duration.
100% on-device privacy
Zero audio is recorded, stored, or uploaded. All ML inference runs locally on the Neural Engine. Your breathing data never leaves your phone.
Control Pause test
Measure your CO2 tolerance with the clinically recognized Buteyko breathing fitness metric. Track your score over weeks and months.
60-second reset
Guided nasal breathing with synchronized haptics. Inhale 4 seconds, exhale 6. Log your mood. See the pattern over time.
Progress and streaks
Charts, heatmaps, and streaks show your breathing journey. Daily check-in reminders build awareness until nasal breathing becomes automatic.
Accessible on iPhone and iPad
One app for both, with layouts that use the larger screen rather than stretching to fill it. Full VoiceOver labelling, Dynamic Type, Reduce Motion, and high-contrast support throughout.
How sleep tracking works
04- 01Place your phone on the nightstandTap Start and go to sleep. The microphone captures audio in 5-second windows through the night.
- 02Three classifiers analyze every windowYAMNet across 521 audio classes, Apple SoundAnalysis for cross-validation, and FFT spectral analysis over the snoring band (100 to 500Hz) and breathing band (500 to 2000Hz). All three must agree before a window is labelled.
- 03Wake up to your breathing reportNasal vs mouth breathing percentage, snoring episodes with duration and intensity, trends across nights, and personalized insights.
- 04Audio is never savedProcessing runs on the Neural Engine in real time. Only statistics are stored. No audio is recorded, uploaded, or transmitted.
Built with serious technology
Three classifiers fused into one decision per window.05FAQ
06How does Nostril track breathing during sleep?
Three independent ML classifiers run on-device: YAMNet, Apple SoundAnalysis, and FFT spectral analysis. All three must agree before a 5-second window is classified.
Is my audio recorded or uploaded?
No. All processing happens on your device using the Neural Engine. Zero audio is recorded, stored, or uploaded.
What is the Control Pause test?
A clinically recognized Buteyko breathing fitness metric that measures CO2 tolerance. Most beginners score 10 to 20 seconds; 40 or above indicates healthy nasal breathing.
What languages does Nostril support?
Nine: English, German, French, Spanish (Spain and Mexico), Portuguese (Brazil and Portugal), Italian, and Chinese.
Is Nostril free?
Free to download with core features. Premium unlocks unlimited sleep history, detailed analytics, and all reminders.
Does Nostril work on iPad?
Yes. Nostril is a universal app for iPhone and iPad, and one subscription covers every device signed in to the same Apple account.
Is Nostril accessible?
Yes. Every control is labelled for VoiceOver, text scales with Dynamic Type, animations respect Reduce Motion, and the interface holds up at high contrast.
Start breathing better tonight
Free to download. iPhone and iPad, iOS 26 or later. Available in English, German, French, Spanish, Portuguese, Italian, and Chinese.