Helys vs Seize Light
Price, ratings, monetisation and update history for both apps, side by side โ with what reviewers say about each.
Helys
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I am Helys, your companion for maintaining optimal vitamin D levels and help you create a healthy and effective habit of safe sun exposure. I am here to empower you and help you harness the power of sunlight for your overall well-being. Main Features: โ Vitamin D Tracking I use a scientific formula which considers your skin type, geographical location, time of day, weather conditions and UV index to provide personalized insights on safe sun exposure durations. โ Personalized Sunscreen Reminders I will remind you to apply sunscreen based on your skin type and current UV index. โ Progress Insights and Reports I want to take care of you and ensure you're meeting your recommended levels of vitamin D. โ User-Friendly Interface I have an intuitive interface, which makes it simple and effortless to navigate and track your vitamin D levels. Disclaimer: I do not provide medical advice. Always consult with a healthcare professional for personalized guidance regarding your vitamin D levels and sun exposure habits.
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 โ 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 โ the part of the day the sun is high enough to make vitamin D โ 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 โข Morning light โ get outside soon after waking to help set your clock; today's target minutes adjust for cloud cover. โข Vitamin-D window โ 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. โข Evening wind-down โ when to dim the lights as part of a wind-down routine. THE LIGHT SCORE A simple, transparent 0โ100 score from three parts โ morning light, daylight total, and evening protection โ 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 โข UV comes from weather-forecast data (Apple Weather), not a sensor. โข Vitamin-D output is an estimate from a model, not a blood test. โข Sun safety first: protection is advised at UV 3+, and the rule is always โ don't burn. โข General wellness and educational use only โ not medical advice. Consult a healthcare professional before making health decisions. PRIVATE BY DESIGN โข No account. No sign-up. โข The solar and vitamin-D math run on your device; only coarse coordinates are sent, for the weather lookup. โข Health data is read-only and never leaves your device, except to sync through your own private iCloud โ and it is never used for advertising. Weather data provided by Apple Weather. Carpe lucem. Seize the light.
Screenshots
Verdict
The clearest difference is in-app purchases: Helys at none against Seize Light's 1. Helys also leads on ads (none vs shown) and iOS requirement (16.0 vs 18.0). Seize Light's advantage is update cadence (every 2 weeks vs every 3 months). On price and device support there is nothing between them.
Scored on Price ยท Rating ยท Positive reviews ยท Number of ratings ยท Update frequency ยท Ads ยท In-app purchases ยท Monetization ยท Best chart rank ยท Devices ยท Requires iOS
Both are free to download. Seize Light sells 1 one-off in-app purchase. Helys asks for nothing beyond the download.
Helys ships an update every 3 months, Seize Light every 2 weeks. The most recent releases landed on November 7, 2026 and November 10, 2026 respectively.
| Parameter | Helys | Seize Light |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 3 months | Every 2 weeks โ better |
| Ads | No โ better | Yes |
| In-app purchases | No โ better | Yes |
| Devices | iPhone | iPhone |
| Requires iOS | 16.0 โ better | 18.0 |
| Further details โ not scored | ||
| Size | 3 MB | 39 MB |
| Age rating | 12+ | 4+ |
| Developer | Antonio Palomba | sebastian totte |
In-app purchases
Helys
No in-app purchases
Seize Light
- Remove Ads$4.99









