Range Freely: ECG Recorder

What it looks like

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

The live screen in landscape: DFA alpha-1 and HRV cards above a running ECG strip with the RR trace — Turn the phone sideways and the chart takes the whole screen: a proper strip chart.

The review screen in landscape in Daylight mode: a wide ECG strip with the RR trace above it — Review in landscape, in Daylight mode, for direct sun.

The live screen in the standard dark theme: DFA alpha-1 and HRV 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.

The live screen in Daylight mode on a light background — Daylight mode: a light, high-contrast theme for direct sun.

ECG zoomed to individual heartbeats with the RR trace above — Review, zoomed to individual beats: P, QRS and T waves at full resolution.

The same zoomed ECG in Daylight mode — The same view in Daylight mode.

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.

Settings: display options for DFA, HRV, the zone bar and Daylight mode — Choose what the live screen shows, and switch to Daylight mode.

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

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, with honest status The α1 readout shows a status word with the number, or holds the number back, so you can see how far to trust it instead of being handed a confident number that means nothing. It is meant for steady effort once you are warmed up. About DFA α1.
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 whether an odd interval lines up with a disturbance in the waveform.
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 chest strap

A Polar H10 is what we recommend and test against. Any Bluetooth strap with a beat-to-beat (R-R) stream gives you DFA and HRV, and a strap that also streams ECG, like the H10, gives you the ECG trace too.

Nothing else

No account and no cloud upload, and no internet connection required to record or review. An optional yearly subscription unlocks unlimited recordings, HRV and export.

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.