HealthBridge

A WHOOP-alternative personal health intelligence app built by reverse engineering the FitCloud Pro BLE protocol

What This Is

A fully standalone Android health tracking app that reads directly from FireBoltt smartwatches over BLE — no cloud dependency, no subscription, your data stays with you.

How It Was Built

Most health apps use official SDKs or cloud APIs. This one doesn't.

1. BLE Interception — Used Burp Suite + Android proxy to intercept smartwatch traffic. Hit certificate pinning.

2. Protocol Reverse Engineering — Cloned htangsmart/FitCloudPro-SDK-Android, decompiled sdk-fitcloud-v3.0.2.aar using jadx, extracted:

   • Proprietary GATT UUID mappings
   • Byte packet structure (header + items)
   • Timestamp calculation formula
   • Data type encodings for HR, steps, sleep, SpO2

3. Android App — Built using decoded protocol + official SDK for connection management

4. AI Layer — Groq (Llama 3) generates personalized recovery coaching using actual sensor data

Features

• Live HR + SpO2 real-time charts
• Recovery Score (athlete-calibrated)
• AI health coaching (knows your name + sport)
• Strain score from workouts
• Sleep tracking + manual input
• 7-day recovery trend
• Ubuntu data pipeline (FastAPI + SQLite)
• Fitness profile (Sedentary → Elite athlete)

Accuracy

HR and SpO2 readings are more accurate than the official FitCloud Pro app in testing.

Tech Stack

• Android (Java), Room DB, RxJava3
• FitCloud Pro SDK (htangsmart)
• Groq API (Llama 3.1)
• FastAPI + SQLite (Ubuntu receiver)
• BLE protocol decoded from SDK source

Supported Devices

• FireBoltt Crusader AMOLED (primary)
• More devices coming (adding WatchProvider abstraction)

Architecture