RawPulse

RawPulse — Live WHOOP heart rate on your Android home screen

RawPulse is a tiny Android app that shows your live heart rate on a home‑screen widget, updating about once per second — something the official WHOOP app does not offer. It also derives extra live metrics that WHOOP doesn’t show in real time, including live HRV.

It works by reading the standard Bluetooth Heart Rate broadcast that a WHOOP 4.0 / 5.0 band emits (the same signal Peloton, Zwift and Garmin read). Nothing goes through WHOOP’s servers, there is no login, and there is no per‑user setup — if you can turn on HR Broadcast in the WHOOP app, RawPulse works.

Unofficial. Not affiliated with, or endorsed by, WHOOP. “WHOOP” is a trademark of its respective owner and is used here only to describe compatibility.

Why not just use the WHOOP API?

The official WHOOP Developer API is cycle‑based (recovery, strain, sleep) and does not expose real‑time or continuous heart rate. Per‑second HR is only available locally, over Bluetooth, via the band’s standard Heart Rate Service (0x180D, characteristic 0x2A37). RawPulse subscribes to that stream directly.

Widgets

All widgets are square‑ish tiles you add to your home screen. They update live while streaming is on.

Widget	Shows
Live Heart Rate	Big BPM number, colour‑coded by heart‑rate zone (the main 1:1 tile)
Live HRV	Rolling RMSSD in ms over the last ~60s — not shown live in the WHOOP app
HR Session	Min / avg / max BPM and elapsed time since you started streaming
HR Zone	Percent of your max HR with a zone‑coloured bar

Heart‑rate zones are derived from your max HR (estimated as 220 − age, editable in the app).

How it works (architecture)

A foreground service holds the BLE connection to the WHOOP and pushes each new reading to the widgets. This is required because Android’s built‑in widget refresh has a 30‑minute minimum — real per‑second updates have to be pushed from a service.
A persistent notification shows the current BPM and a Stop button.
WhoopHrManager scans for the band’s HR broadcast, connects, and decodes 0x2A37.
HrRepository is the shared source of truth; HrService and the widgets read from it.

Trade‑offs to know:

One receiver at a time. While RawPulse is connected, your WHOOP can’t also broadcast to another device (Peloton, Zwift, a watch, etc.) simultaneously.
Battery. A persistent BLE connection plus ~1 Hz widget redraws uses noticeably more battery than an idle phone. Stop streaming from the notification when you’re done.
Range. If the band goes out of Bluetooth range, the widgets show the last value / -- and the app auto‑reconnects when it’s back.

Requirements

A WHOOP 4.0 or 5.0 with an active membership, with Heart Rate Broadcast enabled in the WHOOP app (device settings → HR Broadcast).
An Android phone on Android 12 (API 31) or newer (e.g. Pixel 9).

Install

RawPulse isn’t on the Play Store (see the license/rebuild note above about zero‑setup distribution) — install it directly:

Option A — Obtainium (recommended, gets you auto‑updates)

Obtainium tracks an app’s GitHub Releases and notifies you (with in‑place updates) whenever a new one is published — no Play Store needed.

Install Obtainium (from its own releases page or F‑Droid).
In Obtainium, tap Add App and paste this repo’s URL: https://github.com/mikelord007/RawPulse
Obtainium will find the latest release’s APK automatically. Install it, and future releases will show up as updates in Obtainium.

Every release APK is signed with the same dedicated RawPulse release key, so updates install cleanly in place without needing to uninstall first.

Option B — Download the APK directly

Grab app-release.apk from the latest GitHub release, transfer it to your phone, tap it in Files, and allow “install from this source.” You’ll need to repeat this manually for future versions (Obtainium does this part for you).

Option C — Build from source

See Build & install (command‑line) below.

Build & install (command‑line, no Android Studio)

You only need a JDK and the Android command‑line SDK tools — not the full IDE.

1. Install a JDK 17

Install Eclipse Temurin 17 (https://adoptium.net). Confirm:

java -version    # should report 17.x

Set JAVA_HOME to the JDK folder if it isn’t already.

2. Install the Android command‑line SDK tools

Download “Command line tools only” from https://developer.android.com/studio#command-line-tools
Unzip to e.g. C:\Android\cmdline-tools\latest\ (the bin folder must sit directly under latest).
Set environment variables:
- ANDROID_HOME = C:\Android
- add C:\Android\cmdline-tools\latest\bin and C:\Android\platform-tools to PATH
Install the needed packages and accept licenses:

sdkmanager "platform-tools" "platforms;android-35" "build-tools;35.0.0"
sdkmanager --licenses

3. Build the APK

From the project root:

# Windows PowerShell / cmd
.\gradlew.bat assembleDebug

# Git Bash / macOS / Linux
./gradlew assembleDebug

The APK lands at:

app/build/outputs/apk/debug/app-debug.apk

(The Gradle wrapper is committed, so you don’t need to install Gradle separately.)

4. Put it on your Pixel 9

Option A — via USB (adb):

On the phone: Settings → About phone → tap “Build number” 7 times to unlock Developer options.
Settings → System → Developer options → enable “USB debugging”.
Plug the phone into the PC, accept the “Allow USB debugging?” prompt.
Install:

adb install -r app/build/outputs/apk/debug/app-debug.apk

Option B — copy the file: transfer app-debug.apk to the phone (email, Drive, USB), tap it in Files, and allow “install from this source”.

5. First run

Open RawPulse, grant Bluetooth + notification permissions.
In the WHOOP app, enable Heart Rate Broadcast.
Tap Start streaming. The BPM should appear within a few seconds.
Long‑press the home screen → Widgets → RawPulse → drag the tiles you want.

Demo mode (in the app) feeds a simulated heart rate so you can verify the widgets update without wearing the band.

Prefer a GUI? Android Studio does steps 1–3 with one Run click, but it’s a multi‑GB install; the command‑line path above is much smaller.

Project layout

app/src/main/java/com/rawpulse/hr/
  ble/WhoopHrManager.kt      # BLE scan/connect + decode 0x2A37
  data/                      # HrRepository, Metrics (RMSSD), Settings, models
  service/HrService.kt       # foreground service, pushes widget updates + notification
  widget/                    # 4 AppWidgetProviders + WidgetUpdater + styling
  MainActivity.kt            # permissions, start/stop, settings, demo mode

Roadmap / possible Phase 2

Recovery / Strain / Sleep widgets via the WHOOP cloud API (OAuth2). Deliberately left out for now because it would require every user to register their own WHOOP developer credentials, which breaks the zero‑setup, easy‑to‑share design.

Privacy

RawPulse collects no data and has no servers — everything happens on your phone. See the privacy policy (or PRIVACY.md directly) for the full policy.

License

MIT — see LICENSE.

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