Comparison

Zero Fast vs FastWindow

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

Head to head
About

Zero Fast

Track your intermittent fasting journey with an AI-powered coach. Get personalized plans, real-time metabolic insights, and science-backed education to support your weight management and metabolic health goals. Log hydration, weight, and mood to optimize your fasting experience.

Highlights
  • AI Fasting Coach
  • Personalized weekly fasting plans
  • Multiple fasting profiles
  • Real-time metabolic tracking
  • Hydration logging
  • Weight and progress dashboard
  • Apple Health integration
Read full description

Your fast, explained as it happens. Zero Fast times your fast, shows you the moment your body switches to fat-burning and ketosis, and lets you race friends in group challenges. No calorie counting. No strict diets.

About

FastWindow

Features
Read full description

FastWindow does one thing. It shows you how long you've been fasting and when you can eat. Every major fasting app has become a wellness platform — coaching subscriptions, quizzes, recipe feeds, and paywall friction. FastWindow strips all of that away. ONE-TAP FASTING TIMER Open the app. Tap start. Done. No quiz about your goals. No onboarding survey. No account creation. Just a clean fasting timer that works. You see two things: • How long you've been fasting (elapsed time) • When you can eat (remaining time) That's it. That's the app. FASTING PRESETS BUILT IN Choose your fasting window in one tap: • 16:8 (16 hours fasting, 8 hours eating) • 18:6 (18 hours fasting, 6 hours eating) • 20:4 (20 hours fasting, 4 hours eating) • OMAD (One Meal A Day) • Custom durations (Pro feature) No coaching. No meal plans. No calorie tracking. Just fasting. FEATURES THAT MATTER • One-tap fasting timer • Live elapsed and remaining time • Fasting presets (16:8, 18:6, 20:4, OMAD) • 7-day fast history at a glance • Calendar heatmap to see patterns • Backdate your start time if you forget to start the timer • Local notifications when your fast ends • No account required. Ever. • No subscription. Ever. FASTWINDOW PRO — One Time Purchase Upgrade once to unlock: • Unlimited fast history (beyond 7 days) • Custom fasting durations (set any hours:minutes) • Weight log with trend visualization • Apple Health export (weight, fasting data) • Advanced stats (average fast length, streak tracking) Pay once. £4.99. Yours forever. No renewal, no monthly fee, no subscription. WHY FASTWINDOW EXISTS The fasting app category has a problem. Every major app pushes you toward: • Subscription upsells (coaching, premium insights, meal plans) • Onboarding quizzes (goals, weight, activity level, dietary preferences) • Wellness bloat (recipes, articles, community challenges, step tracking) FastWindow rejects all of that. If you need a fasting coach, use Zero. If you want recipes and meal plans, use Fastic. If you want community challenges, use BodyFast. But if you just want to know how long you've been fasting — and that's it — FastWindow is for you. PERFECT FOR • People practicing intermittent fasting (16:8, 18:6, OMAD, etc.) • Users frustrated by fasting app subscriptions • Anyone who wants a timer, not a wellness platform • People who value simplicity over features • Users tired of onboarding quizzes and paywalls WHO FASTWINDOW IS NOT FOR FastWindow does not provide: • Coaching or fasting advice • Meal plans or recipes • Calorie tracking or macros • Community features or challenges • Water intake or step tracking • Body measurements beyond weight If you need those features, consider Zero, Fastic, or BodyFast. FastWindow is intentionally minimal. PRIVACY & SIMPLICITY • No account creation required • No email, no password, no profile • All data stored locally on your device • No cloud sync (intentional — keeps it simple) • No third-party analytics or tracking • Offline-first design NO SUBSCRIPTION MEANS NO SUBSCRIPTION Other fasting apps say "free" but push monthly subscriptions for basic features like custom fasting durations or history beyond 7 days. FastWindow is different: one optional upgrade, one price, lifetime access. No coaching upsells, no premium tiers, no renewal fatigue. Free version: 7-day history, preset durations (16:8, 18:6, 20:4, OMAD), basic timer Pro version: £2.99 once, everything unlocked, forever MEDICAL DISCLAIMER FastWindow is not medical advice. Consult a healthcare professional before beginning any fasting program, especially if you have a medical condition or take medications. SUPPORT & CONTACT Questions? Feedback? Contact us at karl@projectsnaplabs.com FastWindow is independently developed with your focus and simplicity as the top priorities. Download FastWindow today and track your fasts without the bloat, subscriptions, or friction.

Screenshots

Zero Fast4 screens
FastWindow4 screens

Verdict

The call

The clearest difference is iOS requirement: FastWindow at 15.1 against Zero Fast's 26.0. On price, ads, in-app purchases 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. Zero Fast sells 2 in-app purchases, starting at $6.99 per month and FastWindow sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Scorecard1 real difference · 9 level
Zero Fast versus FastWindow: the parameters behind the verdict, then further details
ParameterZero FastFastWindow
PriceFreeFree
Rating5.0 (1 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings1 — better—
Update frequencyEvery 2 weeks—
AdsNoNo
In-app purchasesYesYes
MonetizationFreemium—
DevicesiPhoneiPhone, iPod — better
Requires iOS26.015.1 — better
Further details — not scored
Size35 MB37 MB
Age rating12+4+
DeveloperAPPE LATTE LIMITEDPROJECTSNAPLABS LTD

In-app purchases

2 purchases

Zero Fast

Subscriptions2
  • Zero Fast Monthly$6.991 Month
  • Zero Fast Annually$49.991 Year
1 purchases

FastWindow

One-time1
  • FastWindow Pro$4.99

Questions

Is Zero Fast free?
Zero Fast is free to download, with in-app purchases available.
Is FastWindow free?
FastWindow is free to download, with in-app purchases available.
Do Zero Fast or FastWindow have ads?
Neither Zero Fast nor FastWindow shows ads.

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