Range Freely: ECG Recorder

What it looks like

Screens from a real recorded session on a pre-release build. Screenshots are from a build in progress and are subject to change.

The review screen in landscape: a wide ECG strip with the RR trace above it — Turn the phone sideways and the chart takes the whole screen — a proper strip chart, in Daylight mode.

The live screen: DFA alpha-1 at 0.74 and HRV RMSSD at 13.3 ms above a running ECG trace — The live screen — DFA α1 and HRV above the running trace, with signal quality and usable-beat percentage along the bottom.

ECG zoomed to four heartbeats with the RR trace above, on a light background — Zoomed to individual beats — P, QRS and T where they should be. Four seconds of a ramp test.

The live screen in Daylight mode, DFA card showing a warming-up countdown — The α1 card holding back until you're warmed up — it says what it's waiting for rather than showing a number that wouldn't mean anything.

Export menu offering Review PDF and Kubios CSV, raw or cleaned — Export a review PDF, or a Kubios-ready CSV — raw, or with cleaning applied.

The in-app manual, open to Getting Started — The manual lives in the app, not on a support page you have to go find.

DFA alpha-1 card reading 0.74 in amber, labelled approximately LT1, declining, beside an HRV RMSSD card — α1 falling through the aerobic threshold — at 0.74 the card turns amber and says so, instead of leaving you to spot it. Captured from a real ride at 117 bpm.

What it does

Records the actual ECG Single-lead ECG streamed from a Polar H10 and written to disk for the whole session — not a rolling preview that forgets what it showed you a minute ago.
Every beat-to-beat interval, classified RR intervals as the strap reports them, with usable-percentage, confidence and gap counts on screen so you can see the quality of what you're collecting while you're collecting it.
DFA α1, gated for honesty The α1 readout stays quiet until the conditions make it meaningful. You don't have to be working hard — you do have to be warmed up past a mid-Zone-1 heart rate for a few minutes, because at rest your breathing dominates the beat-to-beat signal. Until then it tells you what it's waiting for instead of handing you a confident number that means nothing.
Four HRV metrics at a glance RMSSD, SDNN, pNN50 and CVRR — tap to cycle between them, with mean RR there too. Live alongside the α1 card, updating as the session runs.
Markers while you work out, regions when you review Tap a marker mid-session; later, zoom to any window and save it as a named region you can jump straight back to.
Review that goes all the way in Pinch and drag from the full session down to a couple of seconds. Outlier intervals are flagged against this session's own waveform, so you can see for yourself whether a spike was your heart or the strap.
Exports that fit real workflows A review PDF for your own records, and Kubios-ready CSV — raw or cleaned — for proper HRV analysis on a desktop.
Apple Watch companion Start, stop and mark from your wrist, with heart rate, zone and the α1 readout visible while the phone stays in a pocket.
Daylight mode A light high-contrast theme for direct sun, because a black screen loses that fight.

What you need

An iPhone

The minimum iOS version will be confirmed at release. Apple Watch is optional — the app is complete without it.

A Polar H10

Or another ECG-capable Bluetooth chest strap. The H10 is what we develop and test against; it's the one we can vouch for.

Nothing else

No account, no subscription to a service, no cloud upload, no internet connection required to record or review.

Pricing

Pricing is set on the App Store, and the App Store is where it will always be correct — including in your own currency and region. When ECG Recorder is live, the download link and its price will appear here.

Not shipped yet. ECG Recorder is in testing. There's no App Store link to give you today; email hello@rangefreely.app and we'll tell you when there is.