Comparison

FastZen vs Mu.

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

Head to head
About

FastZen

This app helps you manage your intermittent fasting journey with custom schedules, progress tracking, and smart reminders. Achieve your weight loss and energy goals with a clean, intuitive interface and motivational features.

Highlights
  • Custom fasting schedules (16:8, 20:4, OMAD, up to 168 hours)
  • Progress tracking with history, streaks, and insights
  • Smart reminders for fasting start and end times
  • Achievements and milestones for motivation
  • Calendar view of completed fasts
  • Light and dark mode
  • Widgets
Read full description

Fasting made simple — and actually enjoyable. FastZen is a beautifully designed intermittent fasting tracker that helps you reach your goals with 16:8, 18:6, 20:4, OMAD and extended fasts. Whether you want to lose weight, build healthier habits or simply feel better, FastZen keeps you motivated from your first hour to your finish line. WHY YOU'LL LOVE FASTZEN • EFFORTLESS TRACKING — Start any fast in one tap. A live countdown and a smooth progress ring show exactly where you are. • LOCK SCREEN & DYNAMIC ISLAND — Follow your fast at a glance with Live Activities, without even opening the app. • APPLE HEALTH SYNC — Fasting sessions and your weight are saved to Apple Health automatically. • BODY TRACKING — Log your weight and water intake and watch your progress trend over time. • 16 PROTOCOLS + CUSTOM PLANS — From beginner-friendly 12:12 and 16:8 to 24, 48 and 72-hour fasts — or create your own schedule. • SMART REMINDERS — Get notified when your eating window opens and closes, and never miss the end of a fast. • CHALLENGES & STREAKS — Stay consistent with weekly challenges and keep your streak alive. • PROGRESS YOU CAN SEE — Weekly charts, a calendar heatmap and clear stats show how far you've come. • PRIVACY FIRST — Your fast is hidden when you switch apps, and you can export your data anytime. HOW IT WORKS 1. Answer a few quick questions so we can tailor a plan to your goals. 2. Pick your protocol — 16:8, 20:4, OMAD or fully custom. 3. Start your first fast and let FastZen handle the rest. FASTZEN PREMIUM FastZen is a subscription app. Every plan begins with a 7-day free trial, and you can cancel anytime in your App Store account settings before the trial ends. Your fasts, history and progress stay saved across all your devices via iCloud. Terms of Use: https://sites.google.com/view/mefjudevllc/terms-conditions Privacy Policy: https://sites.google.com/view/mefjudevllc/privacy-policy

About

Mu.

Features
Read full description

Mu. Mu. is a daily log for the things that affect how you feel: track mood, symptoms, habits, medications — and let patterns emerge naturally over time. Simple. Modern. Free. Private. —WHAT YOU CAN DO— *Track Events Choose what to track: insomnia, anxiety, stress, medication, or create custom events that matter to you. Log as many or as few as you like. *Log Your Mood Record how you feel on a scale of 0 to 10. *Write Notes Attach a note to any logged event or mood. *Explore Patterns View your data with intuitive charts and statistics. Filter by event type and adjust the time period to see what influences your wellbeing. *Export Your Data Download your history as a CSV or a detailed PDF report — complete with mood charts, color-coded grids, and event heatmaps. Pick the period and the events you want to include. *Apple Watch Companion Log events and your mood directly from your wrist. Data syncs automatically with your iPhone. —SOME WAYS TO USE MU.— • Mood Tracker • Medication Tracker • Pain Tracker • Symptom Journal —PRIVACY FIRST— Your data never leaves your device or iCloud. Without an account or internet connection, Mu. works entirely offline. All your entries—mood scores, events, notes—stay with you. —DESIGNED FOR YOU— Built to be intuitive and calming, by someone who uses it daily. —MEDICAL DISCLAIMER— This app is not a substitute for professional medical advice, diagnosis, or treatment. If you have concerns about your health, please consult a qualified healthcare provider. —LANGUAGES— English, French, Spanish, Arabic —CONTACT & SUPPORT— Questions or feedback? Reach out to us directly from the app's Contact section or via our website, Reddit, Discord or Instagram.

Screenshots

FastZen3 screens
Mu.4 screens

Verdict

The call

The clearest difference is in-app purchases: Mu. at none against FastZen's 5. Mu. also leads on device support (3 vs 1) and iOS requirement (18.6 vs 26.0). On price, update cadence and ads 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. FastZen sells 5 in-app purchases, starting at $1.99 per 7 days. Mu. asks for nothing beyond the download.

UpkeepUpdate frequency

FastZen ships an update every 5 days, Mu. every 10 days. The most recent releases landed on October 9, 2026 and October 28, 2026 respectively.

Scorecard3 real differences · 6 level
FastZen versus Mu.: the parameters behind the verdict, then further details
ParameterFastZenMu.
PriceFreeFree
Rating5.0 (9 ratings) — better—
Number of ratings9 — better—
Update frequencyEvery 5 days — betterEvery 10 days
AdsNoNo
In-app purchasesYesNo — better
MonetizationFreemium—
DevicesiPhoneiPhone, iPad, Apple Watch — better
Requires iOS26.018.6 — better
Further details — not scored
Size27 MB34 MB
Age rating4+12+
DeveloperMefjuDev LLCLiminal Pictures

In-app purchases

5 purchases

FastZen

Subscriptions4
  • Weekly3 Days trial$1.997 Days
  • Monthly$2.991 Month
  • 3 Months$7.993 Months
Show 1 more
  • Yearly$19.991 Year
One-time1
  • Lifetime$39.99
None

Mu.

No in-app purchases

Questions

Is FastZen free?
FastZen is free to download, with in-app purchases available.
Is Mu. free?
Mu. is free to download, with no in-app purchases.
Do FastZen or Mu. have ads?
Neither FastZen nor Mu. shows ads.
Which is updated more often, FastZen or Mu.?
FastZen ships an update every 5 days, and Mu. every 10 days. Most recently, FastZen was updated on October 9, 2026 and Mu. on October 28, 2026.

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