Rexx — smart fitness band app for Android and iOS. Your device.Your data.Your recovery.
Rexx turns your fitness device into a full health companion — continuous vitals, sleep, workouts, recovery score and fitness age. Everything lands on your phone first, so your dashboard works with or without a network.
Heart rate
62bpm
Recovery
78%
Steps
8,412
Live
Measuring
Understand your body like never before.
One screen that answers the only question that matters in the morning: am I recovered, or not? Tap a metric to see it on the phone.
Good morning, Michael
Your body, at a glance.
Recovery
78
Readiness score
Today’s activity
8,412 steps
78% · Good
Rest HR
54 bpm
HRV
68 ms
Sleep
7h 42m
You recovered well. A moderate session suits today.
Every signal your device sends, in one app.
Heart rate, sleep, blood oxygen, stress, recovery and fitness age — each one read by the device, stored on your phone, and waiting on a single screen.
- Heart Rate62 bpm
- Health MonitorSpO₂ 98%
- ECGNormal
- One Key MeasurementTap once
- Steps8,412
- GPS Running5.2 km
- Calories2,140
- Recovery78
- Stress MonitorLow
- Fitness Age27
- Friends & FamilySoon#3
Built for the metrics that actually change behaviour.
No watch faces, no app store, no firmware menus. Rexx does fitness — and does it without a connection.
Recovery score
A 0–100 readiness read from resting heart rate, HRV and sleep.
- Fitness age27Calendar age31
Fitness age
How your cardio fitness compares to your calendar age, recalculated locally.
Sleep & vitals
Sleep stages, resting heart rate, blood oxygen and temperature trends.
Workouts
Start a session on the phone or import one the device recorded on its own.
- 06:40Alarmevery 50mMoveevery 2hWater
Reminders
Alarms, sedentary nudges and drink-water reminders, written to the device.
- Shared ✓
Reports you can share
Export a clean health report and hand it to the clinician of your choice.
Offline-first, by design.
Most fitness apps show you a spinner when the network drops. Rexx treats the device and your phone as the source of truth — the server is just a backup.
- 01
Pair your device
Scan over Bluetooth, bind the device and Rexx reads its capabilities — battery, firmware and which sensors it actually has.
- 02
Sync happens quietly
On connect, Rexx pulls today's data and backfills history from the device, then writes every sample to the local database.
- 03
Your dashboard reads locally
Charts and scores are rendered from on-device storage — never from a live request. Airplane mode changes nothing.
- 04
Cloud is optional backup
Snapshots are pushed to your Rexx account in the background, best-effort. If the push fails, your data is still safe on the phone.
Questions, answered.
Yes. Your device syncs over Bluetooth and everything is written to a local database on your phone. The dashboard, history and scores all read from that store, so they work fully offline.
Put your device to work.
Pair in under a minute. Your first recovery score lands after one night of sleep.