Comparison

Fast AI vs Flex3

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

Head to head
About

Fast AI

This app helps users achieve weight loss and improve well-being through intermittent fasting. It provides tracking, scheduling, and detailed analytics to guide users through various fasting plans. The app aims to make fasting a natural and effective part of a healthy lifestyle.

Highlights
  • Intermittent fasting tracker
  • Weight monitoring
  • Fasting and food window notifications
  • Detailed analytics
  • Multiple fasting schemes (e.g., 16/8)
  • Fasting schedule
  • Apple Health weight sync
Features
Read full description

FastMe - YOUR PROFESSIONAL FASTING ASSISTANT WHY CHOOSE FASTING? The most natural way to lose weight and keep fit. Improve your body and brain function. Burn your body fat reserves. Boost your growth hormone. Lose weight without diet and exercise. Make you feel more active. No need to count calories intake. FEATURES OF FASTING TRACKER - Intermittent fasting tracker - Weight monitoring - Notifications about start/end of fasting and food window - Detailed analytics - Most popular 16/8 scheme and more - Fasting schedule - Weight sync with Apple Health IS IT EFFECTIVE? It’s proven that this healthy lifestyle leads to fast weight loss. During fasting, as your glycogen depletes, your body switches to ketosis, which is referred to as the body's "fat-burning" mode. This is an effective way to burn fat. IS IT SAFE? Yes. It’s the most natural and safe way to lose weight. Studies show that eating all the time makes your body unable to take a break from digesting. When you fast, you just take a break from eating, it takes some of the load off your liver. CAN I USE FASTING TRACKER? With various fasting plans, fasting tracker is suitable for beginner and experienced, men and women. It guides you through your plan. No need to change your diet, you can easily stick to it. Disclaimer The contents of this app are intended for informational purposes only and not for the purpose of rendering medical advice. If you have any health issues, please consult your doctor before fasting and making any medical decisions. START A FREE TRIAL to familiarize yourself with all the app’s features. UNLIMITED ACCESS MEMBERSHIP SUBSCRIPTION Subscription can be canceled anytime. Payment will be charged to your iTunes Account at confirmation of purchase. Your subscription automatically renews unless auto-renewal is turned off at least 24 hours before the end of the current subscription. Your account will be charged for a renewed subscription within 24 hours prior to the end of current subscription. You can manage your subscription and switch off the auto-renewal by accessing your account settings after purchase. You cannot cancel the current subscription during the active subscription period. Any unused part or time-span of a free trial period will be forfeited, as soon as you purchase a subscription. All personal data is protected in accordance with the Terms of Use and Privacy Policy: Terms Of Use - https://docs.google.com/document/d/1m7ZBk0KB3KTmMfxwOvNmLuwMqQFwb-pPfbx66ZwiRtY Privacy Policy - https://docs.google.com/document/d/1pRTTuB8JbbtRMf63WT39JTws1sGbNceciEgRFeGIjXI

About

Flex3

Features
Read full description

Flex3 is the go to app for all fitness trainer looking to enhance their clients' experience with classes. With over 80+ workouts with detailed instructions, Flex3 gives trainers and clients a rich set of easy to use features. Flex3 also aids progress tracking and helps solve consistency problems.Watch your clients' hard work pay off! Track their progress effortlessly through detailed metrics, and milestones. Celebrate achievements and stay focused on thier journey to a stronger and fitter.

Screenshots

Fast AI4 screens
Flex33 screens

Verdict

The call

The clearest difference is in-app purchases: Flex3 at none against Fast AI's 5. Flex3 also leads on iOS requirement (12.0 vs 14.0). Fast AI's advantage is update cadence (every 2 weeks vs every 5 weeks). On price, 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. Fast AI sells 5 in-app purchases, starting at $5.99 per 7 days. Flex3 asks for nothing beyond the download.

UpkeepUpdate frequency

Fast AI ships an update every 2 weeks, Flex3 every 5 weeks. The most recent releases landed on October 20, 2026 and May 28, 2026 respectively.

Scorecard3 real differences · 7 level
Fast AI versus Flex3: the parameters behind the verdict, then further details
ParameterFast AIFlex3
PriceFreeFree
Rating4.3 (120 ratings) — better—
Positive reviews7.1% of reviews—
Number of ratings120 — better—
Update frequencyEvery 2 weeks — betterEvery 5 weeks
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchases—
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS14.012.0 — better
Further details — not scored
Size101 MB29 MB
Age rating4+17+
DeveloperKiryl SalaveiAravind Athreya

In-app purchases

5 purchases

Fast AI

Subscriptions5
  • Simple intermittent fasting3 Days trial$5.997 Days
  • Intermittent Fasting 1 Month$12.991 Month
  • Personal Fast Program 3 Month$19.993 Months
Show 2 more
  • Intermittent Fasting + Tracker$35.991 Year
  • Intermittent Fasting Annual$49.991 Year
None

Flex3

No in-app purchases

Questions

Is Fast AI free?
Fast AI is free to download, with in-app purchases available.
Is Flex3 free?
Flex3 is free to download, with no in-app purchases.
Do Fast AI or Flex3 have ads?
Neither Fast AI nor Flex3 shows ads.
Which is updated more often, Fast AI or Flex3?
Fast AI ships an update every 2 weeks, and Flex3 every 5 weeks. Most recently, Fast AI was updated on October 20, 2026 and Flex3 on May 28, 2026.

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