NOSTRIL / LAST UPDATED 11 AUGUST 2026

Privacy Policy

Nostril listens to your breathing while you sleep. That deserves a plain explanation of what happens to the sound, so here it is without the boilerplate.

THE SHORT VERSION
Nostril analyses microphone audio entirely on your iPhone or iPad, in real time. No audio is recorded, saved, or sent anywhere, not to us and not to anyone else. We run no servers for Nostril and hold no account for you. The numbers Nostril produces stay on your device, and sync only to your own private iCloud if you have iCloud enabled.

Who is responsible

Nostril is published by DeadPixel Studio UG (haftungsbeschränkt), Berlin, Germany, registered at Amtsgericht Charlottenburg under HRB 279669 B, VAT ID DE459996624. Managing director: Rouzbeh Abadi.

We are the controller for the purposes of the GDPR. You can reach us at [email protected]. The full postal address is on our Imprint.

Microphone and audio

When you start a sleep session, Nostril uses your microphone. Audio is processed in short windows by machine learning models that run on your device: YAMNet via CoreML, Apple's SoundAnalysis, and a spectral analysis pass. All of it executes on the Neural Engine and CPU of your own device.

Each window is turned into a label, for example nasal breathing, mouth breathing, or snoring, and the audio itself is discarded immediately. Nostril does not write audio to disk, does not keep a recording, and does not transmit audio off the device. There is no server that could receive it, because we do not operate one for this app.

iOS will ask for microphone permission before any of this happens, and you can withdraw it at any time in Settings. Without it, sleep tracking simply does not run.

What Nostril stores, and where

Nostril keeps the results of that analysis so it can show you trends: session times and durations, the proportion of nasal versus mouth breathing, counts and intensity of snoring episodes, your Control Pause scores, breathing reset sessions, any mood you log, and your streaks and reminder settings.

This is stored locally on your device. If you have iCloud enabled, it syncs through Apple's CloudKit into your own private iCloud database, so your history follows you between your devices. That data sits in your Apple account, under Apple's terms, and we cannot read it. Turning off iCloud for Nostril keeps everything on the one device.

Subscriptions

Nostril is free to download. Premium features are sold as an auto-renewing subscription through Apple. Apple handles the purchase, the payment and the renewal, and Apple is the party that receives your payment details. We never see your card, your billing address, or your Apple ID. We receive only anonymous, aggregated sales reports from Apple, which cannot be traced back to an individual.

To keep track of whether a subscription is active, the app uses RevenueCat as our processor. When you buy, restore or renew, RevenueCat receives the App Store transaction and a randomly generated identifier for your install. It does not receive your name, your email address or your payment details, and it cannot link the purchase to your Apple ID. Their privacy policy is at revenuecat.com/privacy.

Analytics

Nostril reports anonymous usage analytics through TelemetryDeck, a privacy-focused analytics provider based in Germany. This is how we learn which screens and features people actually use, so we know what is worth improving.

What is sent: the name of a screen you opened or an action you took, such as that a breathing session started, which pattern it used and how many minutes it ran. With each event the SDK attaches your device model, operating system version, app version, language, country, time zone, screen size, colour scheme, which accessibility settings are switched on, and counts of how many sessions and distinct days you have used the app. It also attaches an identifier derived by hashing your device identifier together with our app identifier, so repeat visits from one device can be counted once. That identifier is not your Apple ID, is not the advertising identifier, and cannot be reversed to identify you.

What is never sent: your name, your email address, your Control Pause seconds, your nasal breathing percentage, your snoring counts, your check-in answers, and any audio. Where a result would be useful to us in aggregate, the event carries a coarse band instead of the reading, for example "healthy" rather than "34.2 seconds". We deliberately do not collect health measurements about you.

TelemetryDeck acts as our processor and stores this data in the European Union. It is not sold, not used for advertising, and not used to track you across apps or websites. Their privacy policy is at telemetrydeck.com/privacy.

This website

This page is served as static files from Cloudflare Pages. It sets no cookies, runs no advertising, and embeds no third-party tracking.

Cloudflare processes your IP address as part of delivering and protecting the site, which is a technical necessity for serving any website and rests on our legitimate interest under Art. 6(1)(f) GDPR. Cloudflare acts as our processor.

What Nostril does not have

Some of this policy is short because the app deliberately leaves things out:

  • No user account. There is nothing to sign up for and no login, so we hold no name, email address or password for you.
  • No crash reporting, no attribution and no advertising. Nostril contains no attribution, advertising or crash-reporting SDK. The only analytics are the anonymous usage events described in section 05.
  • No Health app access. Nostril does not read from or write to HealthKit, and never asks for that permission.
  • No tracking. We do not use the advertising identifier and do not track you across apps or websites.

We also do not sell data, share it with advertisers, build profiles, or use your data to train machine learning models. The models inside Nostril are fixed at release; using the app sends nothing back to improve them.

Your rights

Under the GDPR you have the right to access, rectify, erase, restrict and port your personal data, and to object to processing. You may also complain to a supervisory authority; ours is the Berlin Commissioner for Data Protection and Freedom of Information.

In Nostril's case these rights are mostly exercised on the device itself: your data is in your hands, and deleting the app, or deleting entries within it, removes it. If iCloud sync is on, you can also clear it from your Apple account. If you believe we hold anything about you and want it addressed, write to us.

Children

Nostril is not directed at children and we do not knowingly collect data from them.

Changes

If this policy changes we will update this page and the date at the top. Material changes will be noted in the app's release notes.