Choosing an app · 5 min read
The best intermittent fasting apps in 2026, honestly compared
There is no best fasting app, only the best one for what you need. On what we saw when we looked in September 2026: Zero is the strongest for longevity depth, Simple for AI coaching, and Fastic for content and community. iFast, which we make, is built for people who have quit a tracker before because one missed day wiped their streak.
Who wrote this, and why that matters
We make iFast. You should read everything below with that in mind, and it is the reason this article does not simply declare us the winner.
A roundup written by one of the entrants that crowns itself best is worth nothing to you, and you would be right to close the tab. What is worth something is a comparison from someone who has actually used all of these, is specific about where the others are better, and is honest about the reader each one suits.
So here is the summary before the detail: if you want the deepest longevity content, Zero. If you want the most capable AI coach, Simple. If you want the biggest library of guides and challenges, Fastic. If you have started fasting three times and stopped because a single missed day reset everything, that is the specific problem we built for.
What separates these apps
Every app in this category has a timer, preset windows, and a chart. Comparing those is how most roundups fill space, and it tells you nothing, because they are all fine.
The real differences are philosophical. Some are longevity products with a timer attached. Some are calorie trackers that added fasting. Some are coaching subscriptions where fasting is one feature. What you are actually choosing is which of those you want, and the timer is the least of it.
The second real difference is how the app treats failure. Every one of these will eventually meet a day where you do not fast, and what happens next is the difference between an app you keep and one you delete.
| App | Built around | Best for |
|---|---|---|
| Zero | Longevity and metabolic health, with expert content | Reading deeply about the science |
| Simple | An AI coach, with fasting as one input | Wanting something to talk to daily |
| Fastic | Content, challenges and community | Motivation from structure and streaks |
| DoFasting | An all-in-one plan: fasting, meals, workouts | Wanting one app to decide everything |
| iFast | The timer and an honest record you can correct | Having quit a tracker before |
Where the others are genuinely better than us
Zero has depth we do not. It has been built around longevity from the start and publishes with named experts attached, and if what you want is to understand metabolic health properly rather than just time a fast, it is the better product. We are not competing on that and pretending otherwise would be silly.
Simple has put more into its AI coach than we have. Ours draws on your own fasts, weight, hydration and activity when it answers, and it is useful, but if daily conversational coaching is the feature you want most, theirs is the more developed product.
Fastic has more content and a livelier community than we do. If what keeps you going is challenges, streak competitions and a feed of other people, that is their strength.
And all of them have been around longer than we have, which means more integrations, more polish in places, and more usage behind their recommendations.
What we do that the others do not
A streak that forgives you. This is the whole thing, and it is not a marketing line. In iFast a fast counts if you reach 80 percent of your goal, not 100, so a 13-hour finish on a 16-hour goal still counts. One missed day in any rolling seven is forgiven automatically. Today never breaks your streak, so you always have the rest of the day. And you earn a freeze for every seven days of streak, up to three saved, each covering one day you did not fast at all.
A streak that resets on a single miss is the mechanic that produces the "I broke it, so why bother" moment, and it is the most common reason people abandon a tracker they were otherwise doing well with. Most fasting apps we have used work that way. Check how the one you are considering handles a missed day before you commit to it, because it is rarely mentioned on the listing page and it is the thing you will meet in week three.
Entries are correctable. Weight, water, meals, steps and completed fasts can all be edited or deleted; workouts pulled in from Apple Health can be deleted but not edited. Forget to end a fast and wake up to a 37-hour session? Fix the times and your streak and averages recalculate. This sounds mundane until it happens to you, and a tracker you cannot correct becomes one you stop trusting.
And the numbers show their working. The calculators cite the actual papers behind each formula, and this blog labels animal studies as animal studies. That is unusual in this category and it is deliberate.
How to choose
Ask what has gone wrong before, rather than which feature list is longest.
If you have never tried fasting, almost any of these will do, and the free tiers are all reasonable. Pick one and start; the app matters far less than beginning.
If you tried and found it boring, you want content and community, which points to Fastic or Zero.
If you tried and did not know what to eat, you want coaching, which points to Simple or DoFasting.
If you tried and it worked until you missed a day and gave up, that is a design problem rather than a discipline problem, and it is the one we set out to fix.
| What happened before | What you need | Where to look |
|---|---|---|
| Never tried it | Anything with a timer | Any free tier, including ours |
| Got bored | Content and community | Fastic, Zero |
| Did not know what to eat | Coaching | Simple, DoFasting |
| Wanted to understand the science | Depth and credibility | Zero |
| Missed a day and quit | A forgiving streak | iFast |
On pricing, and a warning
We have deliberately not printed prices here. They change often, they vary by country, and a comparison article carrying stale numbers is worse than one carrying none. Check the App Store listing before you subscribe.
The warning is more useful than any figure. Across this category we have seen annual plans presented so that the monthly-equivalent price is the number you notice and the billed total is not. Before you agree to anything, find the amount you will actually be charged and the date it renews. If you have to hunt for that, take it as information about the company.
All of these apps, including ours, have free tiers that will time a fast. You do not need to pay anything to find out whether fasting suits you.