Prism vs Vitamin D Window Widget
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Prism
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Prism is an elegant utility that transforms your daily sunlight exposure into a journey of discovery. By syncing seamlessly with your Apple Watch, Prism helps you balance your light intake and well-being effortlessly. Key Features 1 Seamless Apple Watch Integration. Automatically syncs Time in Daylight using Apple Watch ambient light sensors for a hands-free tracking experience. 2 Dynamic iPhone Widgets. Stay connected with beautiful Home Screen and Lock Screen widgets that show your progress at a glance. 3 Spirit Evolution. Your sunlight data nourishes unique Spirits. Unlock various visual forms as they evolve based on your daily activity. 4 Environmental Insights. View real-time local UV Index and sunset data to plan your outdoor day safely. 5 Secure HealthKit Sync. Prism integrates deeply with the Apple Health app to store and visualize your light exposure data securely. Disclaimer. All data is for informational purposes only. Please consult a professional before making health decisions. information about the auto-renewable nature of the Premium Subscription: Subscription period: 1 month. Price: $1.99 per month (or local equivalent). Payment will be charged to iTunes Account at confirmation of purchase. Subscription automatically renews unless auto-renew is turned off at least 24-hours before the end of the current period. Account will be charged for renewal within 24-hours prior to the end of the current period. Terms of Use (EULA): [https://superficial-restaurant-956.notion.site/Privacy-Policy-2f3f52245d5580b1ae9ac299a0408cff?source=copy_link]. Privacy Policy: [https://superficial-restaurant-956.notion.site/Terms-of-Use-EULA-2f3f52245d558073aa26f42eb6149f80?source=copy_link].
Vitamin D Window Widget
This app displays the optimal times of day for natural vitamin D production based on your location and the sun's elevation. It offers real-time sun schedules, smart widgets for home screen access, and notifications to help you maximize your sun exposure.
- Real-time sun schedule
- Smart widgets
- Daily schedule updates
- Dynamic Island countdown
- Location-based calculations
- Offline functionality
- Solar-themed design
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Vitamin D Window shows you the exact hours when sunlight is strong enough for natural vitamin D production at your location. Set up the app and the widget and enjoy the time window in a snapshot. HOW IT WORKS The app calculates solar elevation angles throughout the day using your GPS coordinates. When the sun is high enough above the horizon (above 45° for optimal conditions, above 30° for partial), you get a clear vitamin D time window with start and end times. FEATURES · Real-time sun schedule — sunrise, sunset, and vitamin D hours at a glance · Solar progress bar — see where you are in the day's sun cycle · Smart widgets (small, medium, large) — check your vitamin D window right from your home screen · Daily schedule — it changes depending on the time of the year · Dynamic island with live countdown of the last minutes of vitamin D in the day · Notifications — don't lose the key moments of the day · Location-based — it changes depending on your location · Works offline — no internet connection required after setup · Beautiful solar-themed design — adaptive gradients that follow the sun through the day WIDGETS THAT KEEP YOU INFORMED Add a widget to your home screen and instantly see today's vitamin D window. The small widget features a progress bar in real time as you move through the vitamin D hours. Medium and large widgets show the full sun timeline with sunrise, sunset, and vitamin D periods. After sunset, widgets automatically switch to show tomorrow's schedule — so you always know what's coming. WHO IS THIS FOR? · Health-conscious individuals who want to optimize their sun exposure timing · People living at higher latitudes where vitamin D windows are seasonal (almost all countries) · Outdoor enthusiasts planning activities around peak sun hours · Anyone curious about their local solar schedule PRIVACY FIRST Your location is used only on your device to calculate solar positions. No data is collected, stored on servers, or shared with third parties. Everything runs locally. — Solar calculations powered by the SunCalc algorithm. Vitamin D window times are based on solar elevation angles and may vary depending on individual factors such as skin type, altitude, and atmospheric conditions.
Screenshots
Verdict
The clearest difference is in-app purchases: Vitamin D Window Widget at none against Prism's 1. Vitamin D Window Widget also leads on iOS requirement (18.0 vs 26.0). Prism's advantage is device support (3 vs 1). On price, update cadence and ads there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Prism sells 1 in-app purchase, starting at $1.99 per month. Vitamin D Window Widget asks for nothing beyond the download.
Prism ships an update every 11 days, Vitamin D Window Widget every 2 weeks. The most recent releases landed on October 11, 2026 and October 10, 2026 respectively.
| Parameter | Prism | Vitamin D Window Widget |
|---|---|---|
| Price | Free | Free |
| Rating | — | 5.0 (2 ratings) — better |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | — | 2 — better |
| Update frequency | Every 11 days — better | Every 2 weeks |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | — | Free |
| Devices | iPhone, iPad, Apple Watch — better | iPhone |
| Requires iOS | 26.0 | 18.0 — better |
| Further details — not scored | ||
| Size | 3 MB | 2 MB |
| Age rating | 4+ | 4+ |
| Developer | 剑炜 陈 | Airhopping, SL |
In-app purchases
Prism
- Prism Premium (Monthly)1 Month trial$1.991 Month
Vitamin D Window Widget
No in-app purchases









