Comparison

Intermittent Fasting Tracker vs 21 Days

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

Head to head
About

Intermittent Fasting Tracker

This app offers a straightforward and private way to track intermittent fasting. It supports iPhone and Apple Watch, providing essential features like widgets, notifications, and progress charts without any advertisements. Ideal for both beginners and experienced fasters, it focuses on a simple user interface to support health and wellness goals.

Highlights
  • Interactive Widgets
  • Notifications
  • Streaks & Badges
  • Charts & Trends
  • Fasting Zones
  • iCloud Sync
  • Dark Mode
Features
Read full description

Track fasting periods with Fasty. No account or sign-up required. Start and stop a fasting timer, set a goal, and review your recorded fasts. Edit entries to correct start and end times and keep a record of your fasting history. Features - Fasting timer: see elapsed time and the time remaining until your chosen goal. - Widgets and Live Activities: check your timer from your Home Screen, Lock Screen, and Dynamic Island on supported devices. - Apple Watch: start and finish fasts, change your goal, and check your current fasting status from your wrist, included for free. - Fasting history: add, edit, and review your recorded fasts. - Charts and trends: explore fasting durations, totals, and averages over time. - Notifications: choose reminders and alerts for your timer and eating window. - Siri and Shortcuts: start and finish fasts and check your current fasting status. - CSV import and export: import existing records or export your data for use outside the app. - Dark Mode: use a light or dark appearance to suit your preference. - Streaks and badges: view summaries and milestones based on your recorded fasts. Additional paid features are available through one-time purchases and auto-renewable subscriptions. Available options, included features, and prices are shown in the app before purchase. Subscriptions renew automatically unless canceled. You can manage or cancel them in your App Store account settings. Health information Fasty is a utility for people who want to track their fasting. It does not recommend fasting or a specific fasting plan and does not provide medical advice. Consult a doctor, registered dietitian, or another qualified healthcare professional about whether and how to fast. Privacy Policy: https://fastyfasting.com/#privacy Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

About

21 Days

Features
Read full description

Build habits that actually stick — 21 days at a time. 21 Days Challenge is a simple and powerful habit tracker designed for real, lasting change. Pick a goal, commit for 21 days, check in daily, and watch your streak grow one day at a time. Whether you want to drink more water, read every day, exercise, meditate, or build any daily routine, 21 Days Challenge keeps you focused, motivated, and consistent. KEY FEATURES • Multiple Habit Challenges Track several habits at once including health, fitness, learning, productivity, mindfulness, and more — all from one home screen. • Streaks & Milestones Watch your streak grow daily. Reach milestones at Day 7 and Day 14, and unlock badges as you build consistency. • Daily Journal Add quick notes, moods, or reflections with each check-in. Discover patterns and understand what works best for you. • Insightful Stats View beautiful charts showing completion rates, mood trends, and overall progress. • Smart Reminders Set custom reminders for each challenge at the times that work best for you. • Private by Default Your data stays on your device. Optional cloud sync is designed with privacy in mind. HOW IT WORKS 1. Pick your challenge — choose a suggested habit or create your own 2. Check in daily — track progress with a single tap 3. Build momentum — strengthen routines through consistency BUILT FOR EVERY KIND OF GROWTH • Health & fitness — water, sleep, movement • Learning & focus — reading, studying, skill-building • Productivity — deep work, discipline, routines • Mindfulness & wellness — meditation, gratitude, journaling • Creativity — writing, drawing, creating • Personal goals — anything that matters to you Start your first 21 days today with 21 Days Challenge — your habit tracker, streak builder, and daily journal for lasting change. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

Intermittent Fasting Tracker4 screens
21 Days4 screens

Verdict

The call

The clearest difference is iOS requirement: 21 Days at 15.0 against Intermittent Fasting Tracker's 17.0. On price, update cadence, ads and in-app purchases 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. Intermittent Fasting Tracker sells 17 in-app purchases, starting at $0.99 per month and 21 Days sells 4 in-app purchases, starting at $0.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Intermittent Fasting Tracker ships an update every 2 weeks, 21 Days every 3 weeks. The most recent releases landed on November 1, 2026 and October 30, 2026 respectively.

Scorecard1 real difference · 9 level
Intermittent Fasting Tracker versus 21 Days: the parameters behind the verdict, then further details
ParameterIntermittent Fasting Tracker21 Days
PriceFreeFree
Rating4.9 (52K ratings) — better—
Positive reviews96.9% of reviews—
Number of ratings52K — better—
Update frequencyEvery 2 weeks — betterEvery 3 weeks
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchases—
DevicesiPhone, Apple WatchiPhone, iPod
Requires iOS17.015.0 — better
Further details — not scored
Size94 MB46 MB
Age rating12+4+
DeveloperKai OelfkeiLoma Technology

Bugs and requests

Intermittent Fasting Tracker

Reported bugs

2 issues
  • Overlapping fasting/eating windows reported
  • Inconsistencies in fasting time calculations

Requested features

4 requests
  • Ability to schedule and set reminders for fasts
  • Option to manually log ketosis levels
  • Export or share fasting data
  • More detailed fasting stage information

21 Days

Not enough reviews yet to summarise bugs or requests.

In-app purchases

17 purchases

Intermittent Fasting Tracker

Subscriptions9
  • Fasty Monthly Donation$0.991 Month
  • Fasty Basic Monthly$0.991 Month
  • Fasty Monthly Donation$1.991 Month
Show 6 more
  • Fasty Basic Monthly$1.991 Month
  • Fasty Monthly Donation$2.991 Month
  • Fasty Basic Yearly$4.991 Year
  • Fasty Basic Yearly$6.691 Year
  • Fasty Pro Monthly2 variants$6.991 Month
  • Fasty Pro Yearly2 variants$19.991 Year
One-time8
  • One Time Donation$4.99
  • Fasty Basic One Time$9.99
  • One Time Donation$9.99
Show 5 more
  • One Time Donation$14.99
  • One Time Donation$24.99
  • One Time Donation$34.99
  • Fasty Pro One Time2 variants$49.99
  • One Time Donation$49.99
4 purchases

21 Days

Subscriptions4
  • Pro Monthly$0.991 Month
  • Ultra Pro Monthly$0.991 Month
  • Pro Yearly$4.991 Year
Show 1 more
  • Ultra Pro Yearly$9.991 Year

Questions

Is Intermittent Fasting Tracker free?
Intermittent Fasting Tracker is free to download, with in-app purchases available.
Is 21 Days free?
21 Days is free to download, with in-app purchases available.
Do Intermittent Fasting Tracker or 21 Days have ads?
Neither Intermittent Fasting Tracker nor 21 Days shows ads.
Which is updated more often, Intermittent Fasting Tracker or 21 Days?
Intermittent Fasting Tracker ships an update every 2 weeks, and 21 Days every 3 weeks. Most recently, Intermittent Fasting Tracker was updated on November 1, 2026 and 21 Days on October 30, 2026.

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