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iPhone 5 images
iPad 5 images
What’s New Version 1.2.1
You can now send feedback right from the app. Head to Settings, then Send feedback, to share ideas or report a problem. Plus small fixes and polish under the hood.
Description
I built RayDay after years of working indoors left me Vitamin D deficient. The fix wasn't another bottle of pills. It was knowing exactly when the sun was high enough so my body could make Vitamin D the way it always has: naturally, on its own. That's all RayDay does: it tells you your daily sun window, personalized to where you live and your skin type, so you can get Vitamin D the way your body was built to.
FEATURES:
• D-Window Calculator: know exactly when Vitamin D production is possible today and tomorrow
• Live Solar Path: a beautiful animated arc showing the sun's position, sunrise, sunset, and the highlighted D-Window
• 7-Day Forecast: see your D-Window for the coming week
• Skin Type Personalization: your Fitzpatrick type determines how fast you make Vitamin D
• Smart Notifications: get alerted before optimal sun days, plus a heads-up when winter's first D-Window returns
• Atmospheric Data: real-time UV index, cloud cover, humidity, and altitude
• Phase-Aware Design: app colors shift with the time of day. Dawn, daytime, sunset, and night
• Home Screen Widget: a quick glance at your D-Window status
• Works Worldwide: accurate for any latitude, including polar regions
HOW IT WORKS:
RayDay uses NOAA solar position algorithms to calculate the sun's altitude throughout the day. When the sun crosses 35° above the horizon, UVB rays penetrate the atmosphere. That's your D-Window for Vitamin D synthesis.
The app factors in your Fitzpatrick skin type to recommend exposure durations that hit your daily IU goal without overexposure.
DISCLAIMER: RayDay is for educational purposes only. Consult a healthcare professional before changing Vitamin D supplementation or sun exposure habits.
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LEGAL:
Privacy Policy: http://www.jakubl.com/privacy.html
Terms of Use (EULA): http://www.jakubl.com/terms.html
SUPPORT:
support@jakubl.com
X: @jakublaszczyk
Accessibility
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Version history 3 versions
Build 887361280v1.2.12026-06-24 15:17:22
You can now send feedback right from the app. Head to Settings, then Send feedback, to share ideas or report a problem. Plus small fixes and polish under the hood.
Build 885690341v1.2.02026-06-18 17:49:01
Big update: RayDay is now built around natural Vitamin D.
• Questionnaire-style onboarding tailors your sun window to your skin type, age, and lifestyle
• Year-view calendar shows when winter shuts the D-Window at your latitude
• Smart notifications keep you on track, even through long no-sun stretches
• Optional AI skin-type detection from a quick photo
• Refreshed look across every screen
Send us feedback right from inside the app.
Build 883861294v1.02026-04-03 17:18:02
No pricing data captured yet — comparisons appear once the app has paid storefronts or in-app purchases.
Availability 1 of 1 storefronts
| Region | Language | Price | Ratings | Avg | Version |
|---|---|---|---|---|---|
US | en-US | Free | 2 | 3.0 | 1.2.1 |
Change log 7 changes · US
✎
releaseNotes updated
You can now send feedback right from the app. Head to Settings, then Send feedback, to share ideas or report a problem. Plus small fixes and polish under the ho
✎
description updated
I built RayDay after years of working indoors left me Vitamin D deficient. The fix wasn't another bottle of pills. It was knowing exactly when the sun was high
✎
subtitle updated
Less Pills, More Sunshine
✎
name updated
RayDay: Vitamin D Tracker
◆
Version 1.2.1 released
You can now send feedback right from the app. Head to Settings, then Send feedback, to share ideas or report a problem. Plus small fixes and polish under the hood.
◆
Version 1.2.0 released
Big update: RayDay is now built around natural Vitamin D.
• Questionnaire-style onboarding tailors your sun window to your skin type, age, and lifestyle
• Year-view calendar shows when winter shuts the D-Window at your latitude
• Smart not
◆
Version 1.0 released