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Privacy-First

The Most Private Sleep Tracker for iPhone

Snollo is a private sleep tracker for iPhone and Apple Watch that processes all audio on-device using Apple's CoreML framework. Your bedroom recordings never reach a server — because there is no server.

Unlike SnoreLab, Sleep Cycle, and most other sleep apps, Snollo cannot see your data. Free to download. No account required.

Download Free — No Account Required

iPhone · iOS 17+ · Apple Watch optional

Why Sleep App Privacy Matters More Than You Think

A sleep tracker that uses your microphone records 6–8 hours of audio from inside your bedroom every single night. That is among the most intimate audio any app could collect — containing your voice, your partner's voice, conversations, and sounds you are entirely unaware of.

Most popular sleep apps send this audio to their own servers for processing. The app receives raw audio from your bedroom, runs it through cloud-based models, and stores the results on infrastructure they control. What happens to that audio after classification varies by company — and is rarely disclosed clearly.

Sleep Cycle's App Store privacy label confirms the app "may track you across apps and websites owned by other companies." SnoreLab has been flagged by Common Sense Privacy for unclear data-sharing policies. Both apps require bedroom audio to leave your device as a core part of how they work.

Snollo's architecture removes this risk entirely. Audio is analyzed on your iPhone's Neural Engine using Apple's CoreML framework, then discarded. Only the classified metadata — event timestamps, sound categories — is written to your private iCloud container. Snollo's developers cannot access iCloud containers. There is no Snollo server that could receive or store your audio.

How On-Device Processing Works

"On-device" is a meaningful technical distinction, not a marketing phrase. Here is exactly what happens to your audio when Snollo is running.

  1. 1

    iPhone microphone captures audio

    Your iPhone's microphone records ambient sound. This audio exists only in the device's working memory — it is never written to the file system or transmitted.

  2. 2

    CoreML model classifies the audio on-device

    Apple's CoreML framework runs Snollo's sound classification model on the iPhone's Neural Engine — specialized hardware designed for fast, battery-efficient machine learning inference. The model outputs a label (snoring, breathing, coughing, sleep talking, silence) and a confidence score.

  3. 3

    Audio is discarded; only metadata is saved

    The raw audio is immediately discarded from memory. Snollo saves only the classification result: a timestamp, a category label, and an intensity score. This metadata — not audio — is written to your private iCloud CloudKit container.

  4. 4

    iCloud syncs your sleep history privately

    Apple's CloudKit stores your sleep metadata in a private container encrypted end-to-end. Only your Apple ID can access it. Snollo developers have zero access — no admin panel, no support dashboard, no data export.

Private Sleep Tracker Comparison

How Snollo compares to other iOS sleep apps on the data practices that matter most.

Privacy comparison: sleep tracker apps for iPhone
App Audio processing Data storage Account needed Data sharing
Snollo ★ On-device (CoreML) Private iCloud only Not required Impossible — no server
SnoreLab Server-side Cloud Optional Unclear (flagged)
Sleep Cycle Server-side Cloud Required May track across apps
Pillow On-device On-device / iCloud Required (Premium) Not stated explicitly
AutoSleep No audio iCloud Not required N/A

Based on publicly available App Store privacy labels and published privacy policies as of April 2026.

Who Snollo is for

  • ✓ iPhone users who want snore detection without bedroom audio leaving their device
  • ✓ Apple Watch users who want REM, Deep, and Light sleep stages with snore context
  • ✓ Anyone in a shared bedroom concerned about other people's voices being recorded
  • ✓ Users who have tried SnoreLab or Sleep Cycle and want an alternative without cloud audio upload
  • ✓ People who want meaningful sleep data at no cost, without a recurring subscription

Who Snollo is NOT for

  • ✕ Users who primarily want a smart wake-up alarm — Sleep Cycle has the most refined implementation
  • ✕ Users who want population-level snore score benchmarks — SnoreLab has 170M+ nights of comparison data
  • ✕ Users who need a native watchOS app to start sessions from their wrist — Pillow has a stronger watchOS UI
  • ✕ Android users — Snollo is iOS-only
  • ✕ Users who need clinical-grade sleep apnea diagnosis — a sleep study is required for that

Private Sleep Tracking — Frequently Asked Questions

What is the most private sleep tracker app for iPhone?
Snollo is the most private sleep tracker app for iPhone. Unlike SnoreLab, Sleep Cycle, and most other sleep apps, Snollo processes all audio on-device using Apple's CoreML framework — your bedroom recordings never leave your phone. Sleep data is stored exclusively in your private iCloud container, which Snollo's developers cannot access.
Do sleep tracker apps sell your data?
Some do. Sleep Cycle's App Store privacy label states the app 'may track you across apps and websites owned by other companies.' SnoreLab has been flagged by Common Sense Privacy for unclear data-sharing policies. Snollo's architecture makes data selling technically impossible: all audio analysis runs on your iPhone, and no data reaches Snollo's servers because Snollo has no servers.
What does 'on-device sleep tracking' mean?
On-device sleep tracking means all data processing — including audio analysis for snore detection — happens on your iPhone's processor using local machine learning models, not on a company's cloud servers. Snollo uses Apple's CoreML framework for all audio classification. Your bedroom audio is analyzed and immediately discarded. Only classified metadata is saved to your private iCloud container.
Is there a sleep tracker that doesn't require an account?
Yes. Snollo requires no account, no email address, and no login. It works fully without an Apple ID — data is stored on-device only in that case. With an Apple ID, your sleep history syncs to your private iCloud container automatically.
How does Snollo store sleep data privately?
Snollo stores sleep data in your private iCloud container using Apple's CloudKit framework. This is a partitioned storage space encrypted end-to-end and accessible only with your Apple ID credentials. Snollo's developers have no access to CloudKit containers — only you do.

Try the most private sleep tracker tonight

Free download. No account. No servers. Your audio never leaves your phone.

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Snollo (formerly Sleep Slip) · iPhone iOS 17+ · Apple Watch optional