whoof

Whoof is an unofficial browser app for people who own a WHOOP 4.0 fitness strap but do not want to pay for a WHOOP subscription. WHOOP sells the strap at low cost and charges a monthly fee to access your own health data through their app. Whoof reads the same data directly from the strap over Bluetooth and displays it in a local dashboard, with no account, no cloud connection, and no ongoing cost.

The strap continuously records heart rate, RR intervals (the time gaps between heartbeats), blood oxygen, and skin temperature. When you open Whoof and connect your strap over Bluetooth, the app pulls any data that was recorded while the strap was out of range, syncs the strap's clock, and starts streaming live readings. Everything is stored in your browser's local storage. From that data, the app calculates HRV (a measure of stress and recovery), a recovery score, and a strain score using publicly documented methods.

The dashboard includes a 30-day calendar view of recovery scores, a daily training recommendation (rest, active, or push), a week-over-week trend summary, and a Poincare plot for visualizing RR interval data. There is also an activity journal where you can log lifestyle factors like sleep quality, alcohol, or hard workouts, and the app calculates how much each factor statistically affects your recovery score once you have enough data points. The HRV number the app shows is one WHOOP normally reserves for paying subscribers.

The app runs entirely in the browser. You can use the hosted version at getwhoof.pages.dev or run it locally with a small Python server included in the repository. Chromium-based browsers are required on Mac and Linux because Safari does not support Web Bluetooth. On iPhone, you can use either the Bluefy browser app or export data from a Mac and import it. An iOS app built on Capacitor is available on a separate branch.

The project is built on top of open research into the WHOOP BLE protocol. It includes clear disclaimers that it is not affiliated with WHOOP and that the metrics are not medically validated. It is MIT licensed.