Comparison

Prism 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

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

Seize Light

Features
Read full description

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 to help protect your sleep. 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 and protect your sleep. 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

Prism4 screens
Seize Light4 screens

Verdict

The call

The clearest difference is in-app purchases: Seize Light at none against Prism's 1. Seize Light also leads on iOS requirement (18.0 vs 26.0). Prism's advantage is ads (none vs shown) and device support (3 vs 1). On price and update cadence 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. Prism sells 1 in-app purchase, starting at $1.99 per month. Seize Light asks for nothing beyond the download.

UpkeepUpdate frequency

Prism ships an update every 11 days, Seize Light fortnightly. The most recent releases landed on September 24, 2026 and September 26, 2026 respectively.

Scorecard4 real differences ยท 2 level
Prism versus Seize Light: the parameters behind the verdict, then further details
ParameterPrismSeize Light
PriceFreeFree
Update frequencyEvery 11 days โ€” betterFortnightly
AdsNo โ€” betterYes
In-app purchasesYesNo โ€” better
DevicesiPhone, iPad, Apple Watch โ€” betteriPhone
Requires iOS26.018.0 โ€” better
Further details โ€” not scored
Size3 MB34 MB
Age rating4+4+
Developerๅ‰‘็‚œ ้™ˆsebastian totte

In-app purchases

1 purchases

Prism

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

Seize Light

No in-app purchases

Questions

Is Prism free?
Prism is free to download, with in-app purchases available.
Is Seize Light free?
Seize Light is free to download, with no in-app purchases.
Do Prism or Seize Light have ads?
Seize Light shows ads; Prism does not.
Which is updated more often, Prism or Seize Light?
Prism ships an update every 11 days, and Seize Light fortnightly. Most recently, Prism was updated on September 24, 2026 and Seize Light on September 26, 2026.

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