Sund is built to keep your data where it belongs — on your device.
Last updated: July 2026
Sund (“the app”) is developed by Çağatay Koca (“we”, “us”, “I”). This policy explains what information the app handles, how it is used, and the choices you have. By using Sund, you agree to the practices described here.
Sund is designed to be fully on-device. There is no Sund account, no login, and no Sund server. We do not operate a backend that collects, stores, or receives your personal data.
To provide its features, Sund works with the following information. All of it is created and kept locally on your device unless a specific section below says otherwise.
Your skin type, sun-reaction preference, outdoor-hours setting, and target tone are stored on your device to personalize sun and tanning guidance. This information is not transmitted to us.
Your logged sun sessions, estimated UV exposure, and estimated vitamin D are calculated and stored on your device to power your history, stats, and tanning progress.
If you choose to use the optional Skin Scan feature, Sund requests access to your camera to capture a photo of your skin.
The analysis runs entirely on your device using Apple’s on-device vision technology. Your photo is not uploaded to any server, is not sent to us or to any third-party AI service, and is not used for facial recognition, identity verification, advertising, or profiling.
The resulting skin-type estimate is saved locally on your device, and you can re-scan or change it at any time.
Sund can write your estimated vitamin D to Apple Health, but only after you explicitly grant permission. You can grant or revoke this access at any time in Settings › Health › Data Access & Devices.
Data written to Apple Health is managed by the Health app under your control, according to Apple’s own privacy protections.
To show accurate UV and sun information for where you are, Sund uses your device location to request a local forecast.
Your location coordinates are sent to Open-Meteo, a weather data provider, solely to retrieve the UV index, cloud cover, and sun-time forecast for that location. Your coordinates are not sent anywhere else, are not stored on any Sund server (there is none), and are not used to identify you. Converting your coordinates into a city name is done on your device by Apple, not by us.
Weather data is provided by Open-Meteo under the CC BY 4.0 license.
Sund offers optional paid subscriptions. Purchases are handled entirely by Apple through the App Store. Your payment details are processed by Apple and are never seen or stored by Sund. We receive only the subscription status needed to unlock premium features on your device.
Sund does not use analytics, advertising, or tracking services. The only third parties involved are:
We do not sell, rent, or trade your information with anyone.
Sund is an informational tool, not a medical device, and does not provide medical advice, diagnosis, or treatment. UV index, vitamin D, tanning progress, and burn-risk figures are estimates for general guidance only and may differ from real conditions.
Do not rely on Sund to prevent sunburn, skin damage, or any health condition. Always use appropriate sun protection and consult a qualified healthcare professional for any decision related to your health, sun exposure, or vitamin D.
Sund is not directed to children under 13, and we do not knowingly handle personal information from children.
Because your information stays on your device, its security is protected by your device’s own safeguards, such as your passcode, Face ID, and iOS encryption. Please remember that no method of electronic storage or transmission is ever completely secure.
Sund may contain links to third-party sites (such as Open-Meteo). We do not operate these sites and are not responsible for their content or privacy practices. We encourage you to review the privacy policy of any site you visit.
We may update this Privacy Policy from time to time. Changes will be posted on this page with an updated date above. Continued use of Sund after changes take effect means you accept the revised policy.
If you have any questions about this Privacy Policy or how Sund handles your information, contact us at: