Comparison

Vitamin D Sun Tracker vs SUNniDAY

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

Head to head
About

Vitamin D Sun Tracker

This app estimates your Vitamin D intake from sun exposure and supplements. It provides real-time UV index, weather, and personalized guidance on optimal sun times and duration to prevent sunburn. Track your progress with historical data and insights.

Highlights
  • Real-time Vitamin D estimates
  • Live UV Index and weather integration
  • Personalized sun timer with sunburn guidance
  • 48-hour UV forecast for optimal exposure
  • Supplement and cofactor tracking
  • Historical data and trend analysis
  • Optional Apple Health integration
Read full description

Vitamin D is the easiest deficiency to fix, but the hardest to track. Bask estimates the Vitamin D you get from sun exposure and supplements, so you can stop guessing and start hitting your goal. Bask is a sun tracker and sun timer that reads the sky, live UV Index, weather, your skin, and what you're wearing to tell you the best time to step outside and exactly how long to stay. SUN SESSIONS + SUN SAFETY - Real-time Vitamin D estimates from our live UV Index, UV tracker, weather, and our sun tracker algorithm - Built-in sun timer with time-to-sunburn guidance so you never overdo it - Time-to-sunburn timer can assist you during your tanning sessions. - Live Activities keep your session on the Lock Screen (iOS 16.1+) FIND YOUR BEST SUN WINDOWS - 48-hour UV forecast of your optimal exposure times with our sun tracker - Get alerts right before your best Vitamin D window opens SUPPLEMENTS + COFACTORS - Quick-log common vitamin D doses in a tap with our vitamin tracker - Track magnesium & vitamin K2 with bite-size education cards HISTORY, STREAKS & INSIGHTS - A clean timeline of every sun exposure session and supplementation. - Track Vitamin D labs to see the impact of your sun exposure and supplement habits. - 7 / 30 / 90-day trends to watch your Vitamin D levels climb PRIVATE BY DESIGN - Your data stays on your device - Optional Apple Health integration - Optional opt-in leaderboard Bask is for educational and wellness tracking only and does not provide medical advice. https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

About

SUNniDAY

Features
Read full description

SUNniDAY tracks real-time UV index and estimates vitamin D production from sun exposure, personalised to your skin type, clothing, and sunscreen. Know your burn limit before you burn. See how much vitamin D you're synthesising minute by minute. Log past sessions and review your vitamin D history over time. Features: • Live UV index from your location • Vitamin D synthesis calculator • Skin type, clothing & sunscreen adjustments • Cloud cover override to fine-tune readings • Log past sun exposure sessions • Vitamin D history chart with body-store trend • Sunrise, sunset and moon phase • Apple Health integration • Home screen widget Based on Sun Day by Jack Dorsey (github.com/jackjackbits/sunday), released into the public domain. Medical disclaimer: SUNniDAY is for general informational and educational purposes only. It is not a medical device and does not provide medical advice, diagnosis, or treatment. All vitamin D and UV figures are modelled estimates, not measurements. Do not use this app to make medical decisions. Always seek the advice of your physician or other qualified health provider before making decisions about sun exposure, vitamin D supplementation, or any health condition — and use this app only in addition to, not as a substitute for, professional medical advice.

Screenshots

Vitamin D Sun Tracker4 screens
SUNniDAY4 screens

Verdict

The call

The clearest difference is in-app purchases: SUNniDAY at none against Vitamin D Sun Tracker's 4. On price, update cadence, ads 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Vitamin D Sun Tracker sells 4 in-app purchases, starting at $4.99 per month. SUNniDAY asks for nothing beyond the download.

UpkeepUpdate frequency

Vitamin D Sun Tracker ships an update weekly, SUNniDAY every 9 days. Both last shipped on October 31, 2026.

Scorecard1 real difference · 9 level
Vitamin D Sun Tracker versus SUNniDAY: the parameters behind the verdict, then further details
ParameterVitamin D Sun TrackerSUNniDAY
PriceFreeFree
Rating4.8 (29 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings29 — better—
Update frequencyWeekly — betterEvery 9 days
AdsNoNo
In-app purchasesYesNo — better
MonetizationFreemium—
DevicesiPhone, iPad — betteriPhone
Requires iOS16.0 — better17.0
Further details — not scored
Size42 MB3 MB
Age rating17+4+
DeveloperGreycloud LLCJesse Wales

In-app purchases

4 purchases

Vitamin D Sun Tracker

Subscriptions3
  • Monthly$4.991 Month
  • Yearly3 Days trial$24.991 Year
  • Yearly3 Days trial$29.991 Year
One-time1
  • Lifetime$79.99
None

SUNniDAY

No in-app purchases

Questions

Is Vitamin D Sun Tracker free?
Vitamin D Sun Tracker is free to download, with in-app purchases available.
Is SUNniDAY free?
SUNniDAY is free to download, with no in-app purchases.
Do Vitamin D Sun Tracker or SUNniDAY have ads?
Neither Vitamin D Sun Tracker nor SUNniDAY shows ads.
Which is updated more often, Vitamin D Sun Tracker or SUNniDAY?
Vitamin D Sun Tracker ships an update weekly, and SUNniDAY every 9 days. Most recently, Vitamin D Sun Tracker was updated on October 31, 2026 and SUNniDAY on October 31, 2026.

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