About CheckNeck
Posture coaching through
hardware you already own.
CheckNeck uses the six-axis inertial sensor inside your AirPods to measure head alignment in real time — no camera, no wearable, no subscription required to start.
01The Insight
Every iPhone owner who listens to music or takes calls already carries a six-axis inertial measurement unit in their ears. The same hardware Apple engineered for Spatial Audio head-tracking contains an accelerometer and gyroscope accurate enough to detect a three-degree forward tilt.
We didn’t build a new sensor. We wrote software that listens to the one you already have.
“The most useful health sensor isn’t the one you buy — it’s the one you’re already wearing.”
02The Problem
Forward head posture is the defining musculoskeletal condition of the desk era. The average human head weighs 4.5–5.5 kg held upright. For every degree of forward tilt, the effective load on the cervical extensors increases non-linearly — at 30° it reaches 18 kg of effective force.
Chronic loading correlates with cervicogenic headaches, thoracic outlet syndrome, and accelerated disc degeneration. An estimated 83% of desk workers who sit for more than four hours daily develop chronic neck discomfort within a decade.
The existing solutions — posture correctors, reminder apps, standing desks — address symptoms. They don’t measure what matters: the real-time angle of your cervical spine.
03The Technology
Apple’s CMHeadphoneMotionManager exposes pitch, roll, and yaw at up to 100 Hz on AirPods Pro. CheckNeck reads all three axes, applies an exponential moving average filter (α = 0.15) to reject jitter, and calculates:
score = max(0, 100 − |pitchDelta| × 4)pitchDelta = smoothed_pitch − calibrated_baseline
Calibration averages 180 samples over three seconds of neutral posture. The baseline is stored in SwiftData and used for every subsequent session. Accuracy: ±2°.
04The Mathematics
The Golden Ratio — φ = 1.618033988749895 — is not an aesthetic choice in CheckNeck. It is the engineering specification.
Every spacing value, every animation timing, every typographic scale step is a φ-derived proportion. The logo’s rotating rings are spaced at φ intervals. The score arc fills at a φ-resonant rate. The EMA filter window is calibrated to match a naturally-balanced temporal frequency.
The interface should feel like it grew — not like it was arranged.
1.618033988749895
05The Application
CheckNeck is iPhone-only, portrait-mode. It requires no account in the free tier and tracks posture in the background via BGTaskScheduler — so it grades your alignment even when the screen is off.
06The Philosophy
We believe health software should be invisible. The best interface is no interface. CheckNeck runs in the background, coaches you with a gentle notification, and otherwise stays silent — no dashboard to check compulsively, no gamified guilt loop.
We chose AirPods not because they were the easiest sensor to work with — they weren’t — but because they were already in your ears. The hardware problem was solved. Our job was to write software worthy of the sensor.
The app is 100% Apple-native: SwiftUI, SwiftData, BGTaskScheduler, StoreKit 2, CMHeadphoneMotionManager. No Firebase. No third-party analytics. No camera permissions requested. Your motion data stays on your device.
“Good design, when it is working, becomes invisible.”
Built by Allevamentum · iOS 17+ · Swift 6.0 · φ = 1.618
Stand tall. Track the drift. Thrive.
Join thousands who’ve swapped chronic slouching for real-time feedback. Free forever — premium when you’re ready.