Privacy Policy — Sextant Vitality

Your app data stays on your device. Sextant Vitality does not collect, store, or share your HealthKit data, your lab values, or your interventions on any server. The contact form is the only feature that ever transmits data outside Apple's services — and only when you tap Send.

Data the App Reads

Sextant Vitality reads the following from Apple HealthKit, only with your explicit permission:

VO₂max
Heart Rate Variability (HRV / SDNN)
Resting Heart Rate
Walking Speed
Sleep analysis (duration, stages where available)
Apple Exercise Time and Step Count
Workout sessions
Body Mass and Body Fat Percentage (optional; reserved for future calculations, not used in v1.0)

You can revoke any of these permissions at any time via iPhone Settings → Privacy & Security → Health → Sextant Vitality.

Data You Enter

Lab results (Total T, ApoB, HbA1c, hs-CRP, etc.) and interventions (sauna, cold plunge, supplements, fasting, etc.) are stored on-device using SwiftData. Your profile (age, biological sex, height, weight, goal) is stored in iOS standard preferences.

Data Storage

All app data — HealthKit-derived scores, lab values, intervention logs, profile, and settings — is stored locally on your device. Sextant Vitality v1.0 does not use iCloud sync; data does not move between your devices. iCloud / CloudKit sync is being considered for v1.1.

Data the App Does NOT Collect

Personal identification information
Location data
Device identifiers or fingerprints
In-app analytics or usage tracking
Crash reports
Advertising identifiers

Third-Party Services

Integration is limited to Apple's first-party services:

Apple HealthKit — for reading the metrics listed above
App Store / StoreKit 2 — for in-app purchases and subscription verification
iOS Local Notifications (UNUserNotificationCenter) — for the optional morning Vitality reminder and weekly bearings notification. Notifications are scheduled and delivered entirely on-device; no remote push servers are involved.

No analytics, advertising, or tracking SDKs are included in the App.

Contact / Feedback Form

When you submit a message through Settings → Contact / Feedback, your message, your optional email address, and basic diagnostic information (app version, iOS version, device model, subscription tier, age band, goal, units) are sent to a developer-operated endpoint at contact.tknzk-contact.workers.dev. This data is used solely to respond to your support request and is retained only as long as needed to resolve it. No data is sent unless you tap Send.

In-App Purchases

All purchases are processed by Apple through the App Store. We do not have access to your payment information, your Apple ID, or any financial data. Purchase verification uses Apple's StoreKit 2 on-device receipts.

PDF Reports & Data Export

The monthly PDF report and JSON / CSV export are generated on-device. Where you choose to send those files (email, AirDrop, your physician, your records app) is entirely up to you and is not visible to us.

Children's Privacy

Sextant Vitality is intended for adults (35–60 years old is the core demographic). No personal data collection occurs from anyone, including minors.

Data Security

Protection relies on iOS encryption and on-device SwiftData storage. No backend servers are involved in processing health data, lab values, or intervention logs. The optional contact form is the only outbound transmission, and only when you voluntarily submit a message.

Your Rights

Revoke Apple HealthKit access via iPhone Settings → Privacy → Health
Disable notifications via iPhone Settings → Notifications → Sextant Vitality
Export all your stored data (interventions, lab results) as JSON or CSV from Settings
Delete all stored data from Settings → "Delete all stored data"
Uninstall the App to permanently remove all local data

Website Analytics

This documentation website (sextant-vitality.tknzk.app) does not currently use any analytics or tracking. The page is static HTML served by GitHub Pages. Standard GitHub server logs may briefly retain IP addresses for security purposes — these are managed by GitHub under their own privacy policy and are not accessible to us.

Changes to This Policy

Updates will be reflected on this page with a revised date. Continued use of the App after changes constitutes acceptance.

Contact

Questions about this policy? Visit our contact page.