Privacy Policy
CyanoSun: Cyanotype Timer · Last updated: October 19, 2026
In short: CyanoSun has no accounts, no analytics, no advertising and no third-party SDKs.
Your logbook, photos and settings stay on your device. The only data that leaves your device is your
location, which is sent to Apple's weather service to get the UV index for your area.
Who is responsible
CyanoSun is developed by Michael Scherer. Contact: 3261177@gmail.com.
What the app uses, and why
- Location (while the app is in use). Used once at launch to request the UV index and cloud cover for your area from Apple WeatherKit. Your coordinates are sent to Apple for this request and are handled under Apple's Privacy Policy. We do not receive or store them on any server. If you decline, you can enter the UV index manually. The coordinates of an exposure are also saved with the matching logbook entry, on your device only.
- Camera. Used only as a light meter: the app reads the brightness of the live camera image to tell whether your print frame is in shade. No video or photo is recorded, saved or transmitted.
- Photos you choose. If you attach a photo to a logbook entry, you pick it with the system photo picker. The app only receives the photos you select, and stores them on your device inside the app.
- Notifications, alarm and Live Activities. Used locally to tell you when an exposure ends and to show the timer on the Lock Screen and Dynamic Island. Nothing is sent to a server.
- Subscription. After a free 5-day trial, CyanoSun offers an auto-renewing subscription. Payment is handled entirely by Apple through the App Store; we never see your payment details or Apple ID. The app checks your subscription status on your device using Apple's StoreKit.
- Trial start date. To keep the free trial from restarting after a reinstall, the app stores the date of its first launch in the iOS Keychain. This is a single timestamp, not linked to your identity. If you use iCloud Keychain, Apple may sync it across your devices.
What we do not do
- We do not collect, sell or share personal data.
- We do not use analytics, advertising or tracking, and we do not include third-party SDKs.
- We do not create accounts or ask for your name or email in the app.
Storage and deletion
Your logbook (exposure settings, notes, photos, coordinates) is stored only on your device. You can delete individual entries in the app. Deleting the app removes the logbook; the trial timestamp described above remains in the Keychain.
Children
CyanoSun does not knowingly collect any data from anyone, including children.
Your rights
Because we do not hold your personal data, there is nothing for us to access, correct or delete on our side. If you have a question about privacy, write to 3261177@gmail.com.
Changes
If this policy changes, the new version will be published at this address with an updated date.