Comparison

SparkFast vs Waterfaster

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

Head to head
About

SparkFast

Features
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Most fasting apps count hours. SparkFast shows you what those hours might mean โ€” estimated biological milestones that give you a reason to keep going. THE SPARK CHART Your fasting hours aren't just numbers. The SPARK Chart visualizes five estimated biological processes โ€” from early insulin changes to deep cellular recycling โ€” based on published research. It transforms a blank timer into a roadmap of what you're working toward. GUIDED REFEEDING Breaking a prolonged fast matters as much as the fast itself. SparkFast provides step-by-step refeeding protocols tailored to your fast duration and dietary preference. No more Googling "how to break a 72-hour fast" mid-fast. AI-POWERED PERSONALIZATION Tell SparkFast about your goals, experience, dietary preferences, and schedule. Our AI creates a custom fasting plan built around your life โ€” not a one-size-fits-all template. CHALLENGES THAT BUILD HABITS Built-in challenges โ€” from a beginner-friendly 5-day start to a 72-hour deep fast โ€” give you structure and milestones to work toward. Track progress, earn achievements, and build consistency. BIOMARKER TRACKING (OPTIONAL) For users who track glucose, ketones, GKI, or Dr. Boz Ratio: type readings in, or import them from your Keto-Mojo meter. See how your metabolic data trends alongside your fasting practice. Most users start without this โ€” it's there when you're ready. ALSO INCLUDES - Intermittent and prolonged fasting schedules (16:8, 18:6, OMAD, 36h, 48h, 72h+) - Apple Health and Health Connect sync for weight, sleep and steps - Step history by week, month and year, with your own entries for the days you walked without your phone - Motivational notifications at key fasting milestones - Eating window and hydration tracking - Stool tracking for gut health awareness - Custom trackers for anything you want to monitor BUILT FROM EXPERIENCE SparkFast was born when co-founder Veronica โ€” who changed her own health through fasting โ€” realized she kept printing charts of estimated biological milestones and sticking them on her kitchen wall to stay motivated during 72-hour fasts. That piece of paper became this app. IMPORTANT The SPARK Chart shows estimated timelines based on published fasting research. Actual metabolic responses vary between individuals based on diet history, metabolic health, and other factors. SparkFast is a motivational and educational tool, not a medical device. YOUR PRIVACY SparkFast does not sell personal data. All information is stored securely and encrypted. SUBSCRIPTION SparkFast requires a subscription for full access. Options include monthly and yearly plans, both with a free trial. Payment is charged to your Apple ID at purchase and renews automatically unless cancelled at least 24 hours before the end of the current period. Manage subscriptions in App Store settings. Terms of Service: https://www.sparkfast.app/terms-of-service Privacy Policy: https://www.sparkfast.app/privacy-policy

About

Waterfaster

Features
Read full description

Water fasting and intermittent fasting, made clear โ€” and no longer something you do alone. Start a fast with one tap and watch the live countdown on your Lock Screen, in the Dynamic Island and on your Home Screen widget. Follow what your body is doing hour by hour โ€” fat burning, ketosis, cellular regeneration โ€” based on published research. FAST TOGETHER โ€” ANONYMOUS BY DESIGN โ€ข Live: see how many people are fasting with you right now โ€ข Your Circle: add friends with a simple code, follow their fast live, send boosts and friendly nudges โ€ข Groups & challenges: chase one goal together โ€” from a 16:8 streak to a 7-day reset โ€ข No profiles, no photos, no feed of strangers. You appear under a generated water name unless you choose otherwise. YOU DECIDE WHO SEES YOU Share everything, hide from one specific friend, or go invisible completely. One tap, any time. NEVER LOSE YOUR PROGRESS Link Apple or Google and restore your history, stats and circle on any device. PICK YOUR PROTOCOL โ€ข Intermittent: 12:12, 14:10, 16:8, 18:6, 20:4 and OMAD โ€ข Water fasting: 24h, 36h, 48h, 72h, 4, 5 and 7 days โ€ข Flex: set or move your finish time while the fast is running ALSO INSIDE โ€ข Live Activity, Lock Screen and Home Screen widgets โ€ข Apple Health: steps, sleep, heart rate, weight and water โ€ข Hydration and electrolyte guidance during longer fasts โ€ข Streaks, trends and your full weight history โ€ข Personal insights and reminders you stay in control of Waterfaster is not medical advice. Talk to your doctor before longer fasts, and never fast on medication without medical guidance. โ€” Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Terms of Service: https://waterfaster.app/terms Privacy Policy: https://waterfaster.app/privacy

Screenshots

SparkFast4 screens
Waterfaster4 screens

Verdict

The call

The clearest difference is device support: SparkFast at 4 against Waterfaster's 1. On price, update cadence, ads and in-app purchases 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

Both are free to download. SparkFast sells 6 in-app purchases, starting at $6.99 per month and Waterfaster sells 3 in-app purchases, starting at $3.99 per 7 days. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

SparkFast ships an update every 6 days, Waterfaster every 11 days. The most recent releases landed on October 4, 2026 and October 5, 2026 respectively.

Scorecard1 real difference ยท 5 level
SparkFast versus Waterfaster: the parameters behind the verdict, then further details
ParameterSparkFastWaterfaster
PriceFreeFree
Update frequencyEvery 6 days โ€” betterEvery 11 days
AdsNoNo
In-app purchasesYesYes
DevicesiPhone, iPad, iPod, Apple Watch โ€” betteriPhone
Requires iOS15.0 โ€” better16.4
Further details โ€” not scored
Size94 MB59 MB
Age rating4+17+
DeveloperSparkFast Technologies LLCAMIT Solutions

In-app purchases

6 purchases

SparkFast

Subscriptions6
  • SparkFast Monthly7 Days trial$6.991 Month
  • SparkFast Annual$48.001 Year
  • SparkFast Annual$51.001 Year
Show 3 more
  • SparkFast Annual$54.001 Year
  • SparkFast Annual$57.001 Year
  • SparkFast Yearly7 Days trial$64.991 Year
3 purchases

Waterfaster

Subscriptions2
  • Waterfaster+3 Days trial$3.997 Days
  • Waterfaster+$44.991 Year
One-time1
  • Lifetime$89.99

Questions

Is SparkFast free?
SparkFast is free to download, with in-app purchases available.
Is Waterfaster free?
Waterfaster is free to download, with in-app purchases available.
Do SparkFast or Waterfaster have ads?
Neither SparkFast nor Waterfaster shows ads.
Which is updated more often, SparkFast or Waterfaster?
SparkFast ships an update every 6 days, and Waterfaster every 11 days. Most recently, SparkFast was updated on October 4, 2026 and Waterfaster on October 5, 2026.

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