Intermittent fasting is a schedule, not a product. The only thing an app strictly has to do is time your fast and your eating window, nudge you at the edges, and show you that you’re keeping it up. That’s a genuinely simple job — which is exactly why “best free fasting app” is worth grading carefully. When the core feature is this cheap to build, the money has to come from somewhere, and too often it comes from a card-up-front trial wearing a “free” label.

So this page grades one thing: can a normal person track their fasts, indefinitely, without entering a payment method? Three of the apps below clear that bar, one is a real free tier with a real ceiling, and one isn’t a free fasting app at all — it’s a subscription with a trial on the front, and we’d rather say so than pad a list.

How to judge a “free” fasting app

A fasting timer is close to a solved problem, so the honest test isn’t “is there a timer” — almost all of them have one. It’s where the timer ends and the upsell begins. Start a fast on the free version and ask: did it make me hand over a card before the clock started? Is the timer itself free, or just the quiz that leads to one? Can I see my history and streak without “upgrade to view”? The genuinely free apps let you run protocol after protocol — 16:8, 18:6, OMAD — and never charge you for the core loop. The traps put the loop behind a paywall and sell you the idea of fasting on the way in.

It’s also worth saying plainly: you do not need a paid app to fast. The fasting communities are full of people who use a free timer, a widget, or literally a phone alarm. The app earns its place by being pleasant and keeping you consistent — not by being mandatory.

Why Zero leads on “free”

Zero is the most-used fasting app, and for “best free” it earns the top spot because its free tier does the actual job rather than teasing it. You pick a protocol from the common presets — 16:8, 18:6, OMAD, or a custom length — start the timer, and it tracks the fast, builds your history, keeps your streak and reminds you at the window edges, all with no card to start. The things behind Zero Plus are the extras: the deeper content library, advanced insights, the coaching-flavored programs. Those can be worth paying for if you want hand-holding, but the core fasting tracker — the reason you downloaded a fasting app — is free, and that’s the distinction this page cares about.

The honest knock, at full weight: Zero leans harder on its premium content and prompts than the minimalists do, so if upgrade nudges annoy you, you’ll notice them. It’s also a fuller, busier app than some people want for what is fundamentally a countdown timer. Who it’s not for: anyone who wants the absolute simplest, quietest timer with no content layer at all — that’s FastHabit’s lane.

The other two that are genuinely free

Window frames the day the way a lot of people actually think about fasting — a fasting window and an eating window — and that mental model clicks for newcomers. The free tier tracks your fasts, logs weight and water, and serves up basic insights without asking for a card. It’s a clean, approachable free tracker; the premium layer adds plans and deeper guidance you can ignore. Who it’s not for: people who want a deep content library or coaching, who’ll find it lighter than Zero.

FastHabit is the deliberately minimal pick, and that’s its whole appeal. It’s a timer and almost nothing else — set a custom fasting duration, get reminders, watch your streak. No academy, no recipe store, no coaching push. The core timer is free; a small paid upgrade unlocks extra customization, but you’re never blocked from the essential loop. For people who find the bigger apps cluttered, this is the calm one. Who it’s not for: anyone who wants education, social features or a polished content experience — by design, it doesn’t have them.

The free-ish one, and the one that isn’t

Fastic earns a 🟡 rather than a ✅. The fasting timer itself works without a card — you can start fasting free, which keeps it out of trap territory — but the features Fastic pushes hardest (the recipe library, the food and menu scanner, the academy content, the richer body-status detail) sit behind Fastic-Plus, and the upgrade prompts are steady. It’s a real free timer with a real ceiling, which is exactly what the middle badge is for. Who it’s not for (free): people who came specifically for the recipes, scanner or coaching content, which is most of what it advertises.

DoFasting is the clearest example of why this category needs the lock badge. The on-ramp is a quiz that leads to a card-up-front trial, and that trial converts to an auto-renewing subscription — quarterly, half-yearly or annual. The public reviews on its own listing and on Trustpilot are heavy with people reporting charges they didn’t expect after a “free” start. It may suit someone who wants a guided program and will pay for it, but it is not an answer to “free fasting app” — keeping the tracker requires a subscription, and a payment method goes in before you’ve timed a single fast. 🔒.

Where people genuinely disagree

The honest split here isn’t really about which timer is best — they’re all competent. It’s about how much app you want around the timer:

  • I want the popular all-rounder with content to grow into → Zero. Generous free timer, optional paid education.
  • I want a clear fasting-window framing, free → Window.
  • I want a timer and nothing else → FastHabit. The minimalist’s pick.
  • I’ll pay for a guided program → a paid app like DoFasting (not free, and that’s the point).

There’s also a recurring, sensible argument in the fasting communities that the best fasting app is often no app at all — a widget or an alarm — because the schedule is the thing, not the software. For someone who keeps forgetting their window, though, a good free timer with reminders is a real help. For where long-term users land on the same apps, The Test Desk is a useful second read, and our health & nutrition category runs the same Free Verdict test across the adjacent tools.