Whoop alternative for iPhone: your Amazfit Helio Strap, read directly

Last updated: 28 August 2026 · The direct link is still being built — what already works today is further down.

People searching for a Whoop alternative are rarely looking for another strap. They are looking for what comes out of it: a recovery score that fits them, an honest reading of their sleep, and a daily strain figure they can steer training by — just without device and membership being chained together.

So LeibFit takes the other route: you bring the hardware — an Apple Watch or an Amazfit band such as the Helio Strap — and the app does the maths on your iPhone. No account, no cloud. And for Amazfit bands the last detour is being removed right now: LeibFit talks to the band directly.

The problem: your Amazfit data depends on the Zepp app

An Amazfit band measures cleanly at night — the values just do not arrive on their own where an analysis app can read them. Today the chain is: band → Zepp app → Apple Health → LeibFit. And one link in that chain is waiting for you.

• The transfer needs you. Zepp reliably writes to Apple Health only when you open the app. Background syncing happens, but not dependably — and at seven in the morning that is the difference between “recovery score is there” and “no data”.
• HRV does not arrive as a night measurement. Since the firmware update that lets the Helio Strap write HRV to Apple Health at all, typically only three to four values per day land there instead of the continuous overnight series — which matches both our own measurements and independent reviews. For a recovery score that compares night with night that is the wrong resolution; any score built on a feed that sparse gets shaky.
• You do not notice. Missing values look like a bad day for the app, not like a missing sync. That is the genuinely annoying part.

Zepp not syncing to Apple Health — what actually helps

Before LeibFit comes into it, the honest order of things: when values are missing today, it is almost always the chain itself, not the analysis app. Zepp is a relay — first the app pulls the data off the band over Bluetooth, then it writes to Apple Health. If step one does not happen, step two cannot. What helps, in order:

1. Check the Zepp app first. Are today's steps in there? If not, the data is still on the band — and no permission in the world changes that.
2. Sync by hand. Open Zepp, pull down on the home screen and wait until the sync finishes. Only then does Zepp write to Apple Health.
3. Re-grant permissions. In Zepp, switch the Apple Health data types off, force-close both apps, reopen Zepp, switch the types back on and confirm the iOS prompt again.
4. Mind the direction. The sync runs one way only: Zepp to Apple Health, not back.

That is the full answer to “Zepp is not syncing” — and at the same time the reason for everything else on this page. Because even with everything set up correctly, one step still needs a human: opening the app. That is exactly the step the direct link removes.

How LeibFit solves it: straight over Bluetooth, at night, without you

Instead of waiting for the manufacturer app, LeibFit collects the values itself. Four steps, each of them verifiable.

1. Connect once, without a password. LeibFit shows you Zepp's own sign-in page. Your credentials go to Zepp's servers only — LeibFit never sees them. What comes back is the device key for your band, and it goes into your iPhone's keychain.
2. At night the app collects the data. A short Bluetooth fetch on a hard time budget: connect, authenticate, ask, hang up. No permanent stream eating your battery — live heart rate belongs in a workout, not in the night.
3. The raw values stay on the device. Heart rate variability, resting heart rate, sleep stages, blood oxygen, respiratory rate, skin temperature, steps, battery level. No server in between — the analysis runs where the data already is.
4. You can see whether it works. The app keeps a record of recent fetches, failures included. “Does this run without me?” is a question about a rate, not about a single tick mark.

How we check that the numbers are right

Reading someone else's device means interpreting bytes — and an interpretation is worth something only once it breaks against a value from outside. So every series is checked against what the Zepp app shows for the same night:

• Blood oxygen: 16 out of 16 values identical.
• Respiratory rate: 13 breaths per minute at 06:28 — to the minute, and the whole overnight curve follows the same shape.
• HRV, resting heart rate, time in bed: matching across several nights (34 ms; 59 and 62 bpm; 440 and 377 minutes).
• Sleep stages: a single fetch returned eight consecutive nights. For the verified nights all four categories match exactly — 82 minutes deep, 269 light, 145 REM, 1 awake. And the span of the most recent night matches, to the minute, the time in bed from an entirely different answer in the same fetch: a cross-check that does not need the Zepp app at all.
• Skin temperature: the sampling grid is proven, the conversion into degrees is not — the Zepp app shows no temperature at all for this band, so there is nothing to check against. That is why only the deviation from your own 30-day average counts towards the assessment: a trend stays right even if the scale should be off by a factor.

Why we draw that line so hard is in our own error log: an earlier find looked like the respiratory rate for two days, because its average matched the Zepp app's overnight mean exactly. The curve did not match — our series sat still while the real one swings between 12 and 17. An average is not a verification. The right series was somewhere else entirely in the protocol.

Which Amazfit devices this means

The connection was built and verified on the Amazfit Helio Strap — the screenless band widely reviewed as a no-subscription Whoop alternative. Technically the whole Zepp OS family speaks the same protocol: the newer Helio Strap Pro as well as the Amazfit watches (Balance, GTR, T-Rex and relatives). Only the Helio Strap has actually been tested, and we claim nothing we have not seen ourselves.

Independently of that, this holds for any device that writes to Apple Health: that route works today — with an Apple Watch, Garmin, Polar, Withings, Oura or an Amazfit band. The direct link is the shortcut for Amazfit, not a requirement for LeibFit.

What it looks like in the app

Screens from the current work in progress. The direct link is not in the App Store yet — everything else on these images is.

What works today — and what the waitlist is for

Honestly: where this solution ends

Connecting to someone else's device without an official interface is not a promise; it is a bet with a good hand. What you should know before relying on it:

• It is experimental, and the app says so. Amazfit and Zepp do not document the protocol and commit to nothing. An update can stop the connection — then the Apple Health route remains.
• The first pairing belongs to the Zepp app. The device key is created during pairing; unpairing or resetting invalidates it.
• Only one side collects. The data connection is effectively exclusive — either Zepp syncs or LeibFit does.
• Zepp's own scores stay out. Values like BioCharge or Exertion are created in their app, not on the band. LeibFit computes its own assessment from raw values instead.
• iPhone only. There is no Android version of LeibFit.
• No diagnosis. The recovery score is guidance for training. LeibFit explicitly does not provide medical readings such as ECG or blood pressure.

Whoop, Zepp, LeibFit — who does what

The three are not on the same shelf, and that is the point. Whoop sells a complete package: device and membership belong together and the analysis happens with them. Zepp sells hardware and ships the app with it; your band's values pass through it, and their scores are created in their cloud. LeibFit sells neither hardware nor cloud — the app is the analysis, and it runs on your iPhone.

In practice: the band is yours and keeps working, whatever you do with your LeibFit subscription. And the numbers LeibFit shows come out of your raw values through a calculation we explain, rather than out of a score handed to you as a black box.

Guidance for your training, not a medical diagnosis. “Whoop”, “Amazfit” and “Zepp” are trademarks of their respective owners, named here descriptively only — there is no affiliation with those companies.