Fast AI vs Flex3
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
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.
- 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
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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
Flex3
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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
Verdict
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
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.
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.
| Parameter | Fast AI | Flex3 |
|---|---|---|
| Price | Free | Free |
| Rating | 4.3 (120 ratings) — better | — |
| Positive reviews | 7.1% of reviews | — |
| Number of ratings | 120 — better | — |
| Update frequency | Every 2 weeks — better | Every 5 weeks |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 14.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 101 MB | 29 MB |
| Age rating | 4+ | 17+ |
| Developer | Kiryl Salavei | Aravind Athreya |
In-app purchases
Fast AI
- Simple intermittent fasting3 Days trial$5.997 Days
- Intermittent Fasting 1 Month$12.991 Month
- Personal Fast Program 3 Month$19.993 Months
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- Intermittent Fasting + Tracker$35.991 Year
- Intermittent Fasting Annual$49.991 Year
Flex3
No in-app purchases









