Comparison

Helys vs Seize Light

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

Head to head
About

Helys

Features
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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.

About

Seize Light

Features
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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 โ€ข Morning light โ€” get outside soon after waking to help set your clock; today's target minutes adjust for cloud cover. โ€ข 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. โ€ข Evening wind-down โ€” when to dim the lights as part of a wind-down routine. THE LIGHT SCORE A simple, transparent 0โ€“100 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 โ€ข UV comes from weather-forecast data (Apple Weather), not a sensor. โ€ข Vitamin-D output is an estimate from a model, not a blood test. โ€ข Sun safety first: protection is advised at UV 3+, and the rule is always โ€” don't burn. โ€ข General wellness and educational use only โ€” not medical advice. Consult a healthcare professional before making health decisions. PRIVATE BY DESIGN โ€ข No account. No sign-up. โ€ข The solar and vitamin-D math run on your device; only coarse coordinates are sent, for the weather lookup. โ€ข 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

Helys4 screens
Seize Light4 screens

Verdict

The call

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

CostPrice ยท In-app purchases ยท Ads ยท Monetization

Both are free to download. Seize Light sells 1 one-off in-app purchase. Helys asks for nothing beyond the download.

UpkeepUpdate frequency

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.

Scorecard4 real differences ยท 2 level
Helys versus Seize Light: the parameters behind the verdict, then further details
ParameterHelysSeize Light
PriceFreeFree
Update frequencyEvery 3 monthsEvery 2 weeks โ€” better
AdsNo โ€” betterYes
In-app purchasesNo โ€” betterYes
DevicesiPhoneiPhone
Requires iOS16.0 โ€” better18.0
Further details โ€” not scored
Size3 MB39 MB
Age rating12+4+
DeveloperAntonio Palombasebastian totte

In-app purchases

None

Helys

No in-app purchases

1 purchases

Seize Light

One-time1
  • Remove Ads$4.99

Questions

Is Helys free?
Helys is free to download, with no in-app purchases.
Is Seize Light free?
Seize Light is free to download, with in-app purchases available.
Do Helys or Seize Light have ads?
Seize Light shows ads; Helys does not.
Which is updated more often, Helys or Seize Light?
Helys ships an update every 3 months, and Seize Light every 2 weeks. Most recently, Helys was updated on November 7, 2026 and Seize Light on November 10, 2026.

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