Comparison

Fasto vs Sunfold

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

Head to head
About

Fasto

Features
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One payment, for life: no subscription, no ads, no account. Fasto is an intermittent fasting timer that explains, hour by hour, what is happening inside your body โ€” and shows you the study behind every claim it makes. WHAT YOU WILL NOT FIND No in-app purchases. No analytics and no trackers. And no servers of ours: your fasts live on your iPhone and, if you turn sync on, in your own iCloud. Never in mine. It works offline. SCIENCE WITH ITS SOURCE ATTACHED The eight metabolic phases cite the published work they rest on, with a direct link to PubMed so you can read it yourself. So does the guide on breaking your fast. And where the literature does not support a claim, Fasto does not make it: no miracle promises, no tidy numbers without evidence. WHILE YOU FAST โ€ข An animated ring with your progress, the phase you are in and a countdown to the next one. โ€ข Eight phases from 0 to 72 h: stabilisation, glycogen, gluconeogenesis, early ketosis, full ketosis, autophagy, deep autophagy and immune renewal. โ€ข Tips that change with the phase, a water counter, and an alert as each phase begins. ON YOUR WRIST AND ON YOUR SCREEN โ€ข An Apple Watch app to start and stop from your wrist, plus watch face complications. โ€ข Home Screen and Lock Screen widgets with a button, without opening the app. โ€ข A Live Activity in the Dynamic Island: your fast always in sight. ON ALL YOUR DEVICES Your fasts sync over iCloud between iPhone and iPad. No account and no servers of ours โ€” it is your iCloud. Change phones and your history is still there. And on iPad it is not the iPhone app stretched out: it has its own two-column layout. Everything scales with Larger Text and works with VoiceOver. WHEN YOU FINISH A summary of what you achieved, the phase you reached, your personal record โ€” and a guide on how to break the fast based on the hours you lasted, because coming off 14 h and coming off 30 h are nothing alike. YOUR HISTORY, WITH INSIGHTS Total, average and record, plus the patterns behind why you tend to stop, how each fast actually felt, and which durations suit you best. Milestones that add up and are not lost the day you slip. YOUR MEASUREMENTS, NO VERDICTS Log your weight and waist whenever you like and see how they change over 30, 90 or 180 days. Fasto shows the numbers and their variation, with no good-or-bad colours and no punishing streaks. The reading is yours and your doctor's. TO TAKE TO YOUR DOCTOR A PDF report with your period, frequency, adherence and longest fasts, ready to share. If your doctor is going to weigh in on your fasting, let them do it with data. A PLAN FOR EVERY PACE 12:12, 14:10, 16:8, 18:6, 20:4, OMAD and custom. Forgot to hit start? Adjust the time whenever you like. IN SIX LANGUAGES English, Spanish, French, Italian, German and Brazilian Portuguese, switchable inside the app. Light theme, dark theme or follow the system. ONE PAYMENT, FOR LIFE You buy Fasto once and it is yours forever. Every feature and every future update is included. No premium tier, nothing behind a paywall, no renewal reminders. IMPORTANT NOTICE Fasto is an informational and educational tool. It is not a medical device: it does not diagnose, treat, cure or prevent any disease, and it is never a substitute for the judgement of a healthcare professional. ALWAYS consult your doctor before starting any fasting routine. This matters especially if you are pregnant or breastfeeding, if you have or have had an eating disorder, if you have diabetes, kidney or liver conditions, if you are under 18, or if you take medication that must be given with food. Use of this app is the sole responsibility of the user. The developer accepts no responsibility for the decisions you make or for the consequences of applying fasting to your health. If at any point you feel unwell, dizzy or weak, stop fasting and seek medical attention.

About

Sunfold

Features
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Sunfold is a quiet, warm intermittent fasting tracker. One ring, one number, and everything you need to know about where you are in your fast. THE TIMER Start when you finish your last meal. Sunfold counts from that moment โ€” close the app, restart your phone, the timer never drifts. A full-screen ring shows how far along you are, and the metabolic phases are marked around it. SCHEDULES 16:8, 18:6, 20:4, 5:2, or set your own length from 4 to 48 hours. Change your schedule mid-fast and the goal moves with you โ€” no need to start over. METABOLIC PHASES Watch your fast move from the fed state through early fasting, fat burning, ketosis and autophagy, with a plain-language explanation of each. Timings are presented as approximations, because that is what they are. HISTORY A streak calendar, total hours, average length, and every fast you have recorded. Add a note and how the fast felt. WEIGHT Optional. Log your weight, see the trend. No goal weight, no BMI, no judgement. WIDGETS AND DYNAMIC ISLAND Your timer on the Home Screen, the Lock Screen, and in the Dynamic Island as a Live Activity, ticking without draining your battery. REMINDERS When your fast is complete, thirty minutes before, and when your eating window closes. All scheduled locally โ€” Sunfold has no push server. PRIVACY No account. No sign-in. No analytics, no advertising, no tracking. Everything you record stays on your device, and you can export it all as CSV or delete it in one tap. SUNFOLD PRO Free forever: the 16:8 schedule and the last seven days of history. Pro unlocks every schedule, unlimited history, charts, the metabolic phases and widgets. Available monthly, yearly, or as a single payment. New subscriptions start with a three-day free trial. Payment is charged to your Apple ID. Subscriptions renew automatically unless cancelled at least 24 hours before the period ends, and can be managed in App Store settings at any time. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://sanchizas007.github.io/Sunfold/privacy/ IMPORTANT Sunfold is a timer and a journal, not a medical device. It does not diagnose, treat or give medical advice. Talk to a doctor before fasting if you are pregnant or breastfeeding, under 18, living with diabetes or taking medication that affects blood sugar, taking medicine that must be taken with food, underweight, or living with a chronic condition. If you have or have had an eating disorder, please seek support before using a fasting app.

Screenshots

Fasto4 screens
Sunfold4 screens

Verdict

The call

The clearest difference is price: Sunfold at Free against Fasto's $2.99. Fasto's advantage is in-app purchases (none vs 3) and update cadence (every 3 days vs every 3 weeks). On ads and iOS requirement there is nothing between them.

Scored on Price ยท Rating ยท Positive reviews ยท Number of ratings ยท Update frequency ยท Ads ยท In-app purchases ยท Monetization ยท Best chart rank ยท Devices ยท Requires iOS

CostPrice ยท In-app purchases ยท Ads ยท Monetization

Sunfold is free to download; Fasto costs $2.99 up front. Sunfold sells 3 in-app purchases, starting at $2.99 per month. Fasto asks for nothing beyond the download.

UpkeepUpdate frequency

Fasto ships an update every 3 days, Sunfold every 3 weeks. The most recent releases landed on November 7, 2026 and October 31, 2026 respectively.

Scorecard5 real differences ยท 2 level
Fasto versus Sunfold: the parameters behind the verdict, then further details
ParameterFastoSunfold
Price$2.99Free โ€” better
Update frequencyEvery 3 days โ€” betterEvery 3 weeks
AdsNoNo
In-app purchasesNo โ€” betterYes
Best chart rank#144 โ€” betterโ€”
DevicesiPhone, iPad, Apple Watch โ€” betteriPhone
Requires iOS17.017.0
Further details โ€” not scored
Size5 MB11 MB
Age rating4+12+
DeveloperRAUL JIMENO MARTINEZOlexandr Zhovnir

In-app purchases

None

Fasto

No in-app purchases

3 purchases

Sunfold

Subscriptions2
  • Sunfold Pro โ€” Monthly3 Days trial$2.991 Month
  • Sunfold Pro โ€” Yearly3 Days trial$29.991 Year
One-time1
  • Sunfold Pro โ€” Lifetime$79.99

Questions

Is Fasto free?
Fasto costs $2.99, with no in-app purchases.
Is Sunfold free?
Sunfold is free to download, with in-app purchases available.
Do Fasto or Sunfold have ads?
Neither Fasto nor Sunfold shows ads.
Which is updated more often, Fasto or Sunfold?
Fasto ships an update every 3 days, and Sunfold every 3 weeks. Most recently, Fasto was updated on November 7, 2026 and Sunfold on October 31, 2026.

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