Comparison

Prism vs Vitamin D Window Widget

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Prism

Features
Read full description

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].

About

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.

Highlights
  • Real-time sun schedule
  • Smart widgets
  • Daily schedule updates
  • Dynamic Island countdown
  • Location-based calculations
  • Offline functionality
  • Solar-themed design
Features
Read full description

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

Prism4 screens
Vitamin D Window Widget4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

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.

UpkeepUpdate frequency

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.

Scorecard3 real differences · 7 level
Prism versus Vitamin D Window Widget: the parameters behind the verdict, then further details
ParameterPrismVitamin D Window Widget
PriceFreeFree
Rating—5.0 (2 ratings) — better
Positive reviews—100.0% of reviews
Number of ratings—2 — better
Update frequencyEvery 11 days — betterEvery 2 weeks
AdsNoNo
In-app purchasesYesNo — better
Monetization—Free
DevicesiPhone, iPad, Apple Watch — betteriPhone
Requires iOS26.018.0 — better
Further details — not scored
Size3 MB2 MB
Age rating4+4+
Developer剑炜 陈Airhopping, SL

In-app purchases

1 purchases

Prism

Subscriptions1
  • Prism Premium (Monthly)1 Month trial$1.991 Month
None

Vitamin D Window Widget

No in-app purchases

Questions

Is Prism free?
Prism is free to download, with in-app purchases available.
Is Vitamin D Window Widget free?
Vitamin D Window Widget is free to download, with no in-app purchases.
Do Prism or Vitamin D Window Widget have ads?
Neither Prism nor Vitamin D Window Widget shows ads.
Which is updated more often, Prism or Vitamin D Window Widget?
Prism ships an update every 11 days, and Vitamin D Window Widget every 2 weeks. Most recently, Prism was updated on October 11, 2026 and Vitamin D Window Widget on October 10, 2026.

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