Read your WHOOP 4.0 strap over Bluetooth. All data stays in your browser. No subscription, no cloud, no middleman.
OpenWhoop reads raw sensor telemetry from the strap you own. Every metric is computed transparently on-device.
Reads heart rate, RR intervals, SpO₂, and skin temperature directly from the strap over Web Bluetooth. No companion app needed.
All data lives in IndexedDB — your browser. No server, no cloud storage, no account. Export and import JSON for full backup portability.
Textbook RMSSD-based HRV computation with Malik artifact filtering. Recovery scored from your 14-day personal baseline — same math, transparent.
Borg-inspired cardiovascular load. Five HR zones with time breakdown, calorie estimates, and ACWR training load ratio to prevent overtraining.
Strap records 1 Hz HR + RR to internal flash 24/7. Walk back in range and OpenWhoop drains the buffer automatically — no data lost.
Ask questions about your recovery, strain, sleep, and stress — grounded in today's actual data. Runs on Cloudflare Workers AI.
Separate exports for raw samples, daily metrics, journal entries, and workouts. Full JSON backup/restore. Your data, your format.
Log alcohol, stress, caffeine, meditation, and more. After enough data, Cohen's d effect size reveals what actually impacts your recovery.
Installable on desktop and mobile. Cache-first for assets, works offline. Push notifications for backfill complete, low recovery, and HR anomalies.
No account, no install required. Open the dashboard, pair your strap, done. Pick the path for your device.
Web Bluetooth works out of the box in any Chromium browser on Mac, Windows, or Linux. Safari and Firefox do not support it.
1. Click Launch Dashboard at the top of this page.
2. Tap your WHOOP band to wake it (it won't show while charging).
3. Click Connect Whoop and pick your strap from the browser's device list.
It pairs, drains any data stored on the strap, and starts streaming. Everything is saved in your browser.
Apple's Safari can't access Bluetooth, so use Bluefy, a free browser with full Web Bluetooth support.
1. Install Bluefy from the App Store (free).
2. Open Bluefy and go to openwhoop.vatsa.online.
3. Launch the dashboard, tap Connect Whoop, and allow Bluetooth when asked.
4. Pick your strap. Your iPhone pairs to it directly over Bluetooth.
OpenWhoop is a Progressive Web App, so you can add it to your home screen or dock and launch it like a native app, with offline support.
iPhone (Bluefy or Safari): Share button, then Add to Home Screen.
Desktop Chrome/Edge: the install icon in the address bar, or menu, then Install OpenWhoop.
The installed app opens straight to the dashboard.
You need: a WHOOP 4.0 strap you own, and a browser with Web Bluetooth (any Chromium browser on desktop, or Bluefy on iPhone). That's it, no subscription, no signup.
Want to self-host or run it locally? See the README on GitHub.
Every metric is computed transparently from raw sensor data. No black boxes.
| Metric | Source | How it's computed |
|---|---|---|
| Heart rate (BPM) | Live BLE packet bytes 1–2 | Direct decode |
| RR interval (ms) | Live BLE packet bytes 3–4 | Direct decode |
| SpO₂ (%) | Live BLE packet byte 5 | Direct decode |
| Skin temperature | Live BLE packet byte 6 | byte − 25 °C offset |
| HRV (RMSSD) | RR intervals during 02–06 local | √(mean of squared successive RR diffs), Malik filter |
| Recovery score | Today's RMSSD vs 14-day baseline | z-score → 0–100 scale |
| Strain score | HR throughout the day | Borg-like load: 21·(1 − e^(−load/100)) |
| Resting HR | 5th percentile of daily HR | Order statistic |
WHOOP's actual algorithms are closed-source — these reproduce the spirit of the metrics using textbook HRV and training-load formulas. Not clinically validated. Not medical advice.