Vitamin D Window Widget vs Seize Light
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
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.
Seize Light
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Get the right light at the right time. Seize Light reads where you are and the sky above you, computes the sun's real position on your device, and shows your daily light windows — when to get outside, and when to wind down. Most sun apps just show today's UV number. Seize Light shows your two windows: a morning-light window to help set your body clock, and the vitamin-D window — the part of the day the sun is high enough to make vitamin D — plus an evening wind-down that tells you when to dim the lights. Your Apple Watch's Time in Daylight turns it into a passive daily habit, with a transparent Light Score and a streak. YOUR THREE WINDOWS • Morning light — get outside soon after waking to help set your clock; today's target minutes adjust for cloud cover. • Vitamin-D window — opens when the sun is high and UV is strong enough, and closes when it isn't (it tells you why). Keep it short and sub-erythemal. • Evening wind-down — when to dim the lights as part of a wind-down routine. THE LIGHT SCORE A simple, transparent 0–100 score from three parts — morning light, daylight total, and evening protection — fed by your Apple Watch's Time in Daylight. Missing data is never held against you. Build a daylight streak and watch your 90-day trend. EVERY NUMBER IS CITED The solar math, the UV model, and the vitamin-D estimate all trace to published science in an in-app "How this works" screen. HONEST BY DESIGN • UV comes from weather-forecast data (Apple Weather), not a sensor. • Vitamin-D output is an estimate from a model, not a blood test. • Sun safety first: protection is advised at UV 3+, and the rule is always — don't burn. • General wellness and educational use only — not medical advice. Consult a healthcare professional before making health decisions. PRIVATE BY DESIGN • No account. No sign-up. • The solar and vitamin-D math run on your device; only coarse coordinates are sent, for the weather lookup. • Health data is read-only and never leaves your device, except to sync through your own private iCloud — and it is never used for advertising. Weather data provided by Apple Weather. Carpe lucem. Seize the light.
Screenshots
Verdict
The clearest difference is ads: Vitamin D Window Widget at none against Seize Light's shown. On price, update cadence, in-app purchases and device support 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. Neither carries in-app purchases, so what you see is what you pay.
Both ship on a similar rhythm, roughly every 2 weeks. The most recent releases landed on October 10, 2026 and October 12, 2026 respectively.
| Parameter | Vitamin D Window Widget | Seize Light |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (2 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 2 — better | — |
| Update frequency | Every 2 weeks | Every 2 weeks |
| Ads | No — better | Yes |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone | iPhone |
| Requires iOS | 18.0 | 18.0 |
| Further details — not scored | ||
| Size | 2 MB | 35 MB |
| Age rating | 4+ | 4+ |
| Developer | Airhopping, SL | sebastian totte |
In-app purchases
Vitamin D Window Widget
No in-app purchases
Seize Light
No in-app purchases
Questions
Is Vitamin D Window Widget free?
Is Seize Light free?
Do Vitamin D Window Widget or Seize Light have ads?
Which is updated more often, Vitamin D Window Widget or Seize Light?
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