Blue2Scale

Track 39 body composition metrics from your Bluetooth scale — right in your browser.

What Is Blue2Scale?

Blue2Scale is a web application that connects to Bluetooth Low Energy (BLE) body composition scales directly from your browser using the Web Bluetooth API. No mobile app installation required — just open the site, step on your scale, and get a complete breakdown of 39 body composition metrics in seconds.

Every measurement captures detailed body composition data including weight, body fat percentage, muscle mass, hydration levels, bone mineral content, visceral fat rating, metabolic age, and full segmental analysis (muscle and fat for each arm, leg, and trunk). All data is stored securely and visualized through interactive charts, trend indicators, and an anatomical body map.

Blue2Scale is free to use at blue2scale.com. Sign in with Google or try a single measurement as a guest without creating an account.

Screenshots

Screenshots coming soon — the app is live at blue2scale.com

Supported Metrics

Blue2Scale captures 39 distinct metrics per measurement, organized into the following categories:

Core Metrics

Metric	Unit	Description
Weight	kg / lbs	Total body weight
BMI	index	Body Mass Index

Body Fat

Metric	Unit	Description
Body Fat	%	Total body fat percentage
Fat Mass	kg / lbs	Absolute fat mass
Subcutaneous Fat	kg / lbs	Fat beneath the skin
Subcutaneous Fat	%	As percentage of body weight
Visceral Fat	rating (1–59)	Fat around internal organs
Android Fat	kg / lbs	Fat in the abdominal region
Gynoid Fat	kg / lbs	Fat in the hip/thigh region
A/G Ratio	%	Android-to-Gynoid fat ratio

Lean & Muscle

Metric	Unit	Description
Lean Mass	kg / lbs	Total non-fat mass
Lean Mass	%	As percentage of body weight
Skeletal Muscle	kg / lbs	Muscle attached to skeleton
Body Cell Mass	kg / lbs	Metabolically active cell mass

Water

Metric	Unit	Description
Body Water	%	Total water as percentage of body weight
Total Water	kg / lbs	Absolute water mass
ECW (Extracellular Water)	kg / lbs	Water outside cells
ICW (Intracellular Water)	kg / lbs	Water inside cells

Bone & Mineral

Metric	Unit	Description
Bone Mineral	kg / lbs	Mineral content of bones
Mineral Mass	kg / lbs	Total mineral mass

Other Composition

Metric	Unit	Description
Skeletal Mass	kg / lbs	Total skeletal system mass
Organ Mass	kg / lbs	Mass of internal organs

Metabolic

Metric	Unit	Description
BMR	kcal	Basal Metabolic Rate
Metabolic Age	years	Estimated metabolic age

Segmental Analysis (5 segments × 3 values = 15 data points)

Segment	Muscle (kg/lbs)	Fat (%)	Fat (kg/lbs)
Right Arm	✓	✓	✓
Left Arm	✓	✓	✓
Trunk	✓	✓	✓
Right Leg	✓	✓	✓
Left Leg	✓	✓	✓

Tested Devices / Compatibility

✅ Hume Body Pod — Fully tested, all 39 metrics supported

Blue2Scale uses the standard Bluetooth Low Energy (BLE) Body Composition Service (UUID 0x181B) and Weight Scale Service (UUID 0x181D). It should work with other BLE body composition scales that implement these standard services, though it has only been verified with the Hume Body Pod.

If you've tested Blue2Scale with another scale, please open an issue to let us know!

Features

Web Bluetooth Connection — Connect directly from your browser, no app install needed
Real-time Measurement — Live weight display with body composition results in seconds
39 Body Metrics — Full body composition breakdown including segmental analysis
Interactive Dashboard — At-a-glance view of key metrics with trend indicators and sparklines
Body Map Visualization — Anatomical silhouette showing segmental muscle and fat data per body region
Trend Charts — Interactive, zoomable charts tracking every metric over time with time range filters (1W, 1M, 3M, 6M, 1Y, ALL)
Dark & Light Themes — Full dark and light theme support with system preference detection
Data Table View — Sortable, filterable history of all measurements with column visibility controls
Data Export — Export as CSV and JSON
Goal Tracking — Set targets for any metric and track progress with visual progress bars
Google Sign-In — One-click authentication with your Google account
Guest Mode — Try a single weigh-in without creating an account (data stored locally)
Privacy First — Your data stays on the server, full account deletion available
Responsive Design — Optimized for desktop, tablet, and mobile with adaptive sidebar/bottom navigation
Unit Toggle — Switch between metric (kg/cm) and imperial (lbs/ft-in) in settings
Measurement Notes — Attach notes to any weigh-in for context

Browser Compatibility

Blue2Scale uses the Web Bluetooth API, which is only available in:

Browser	Supported	Minimum Version
Google Chrome	✅ Yes	56+
Microsoft Edge	✅ Yes	79+
Opera	✅ Yes	43+
Firefox	❌ No	No Web Bluetooth API
Safari	❌ No	No Web Bluetooth API

Web Bluetooth requires HTTPS. The app at blue2scale.com is served over HTTPS. If self-hosting, you must configure SSL.

How It Works

User clicks "Connect Scale" → the browser's Web Bluetooth device picker appears
User selects their BLE scale from the list
App connects via GATT and subscribes to Body Composition Service notifications
User stands on scale and grabs the handle electrodes (for scales with handles)
Scale transmits weight and bioelectrical impedance data over BLE
App parses the raw BLE data and calculates all 39 body composition metrics using BIA (Bioelectrical Impedance Analysis) algorithms
Results are displayed instantly — user can save to their account or continue as guest

All BLE communication happens locally in the browser. Raw measurement data is only sent to the server when the user explicitly saves a measurement.

Tech Stack

Layer	Technology
Frontend	Vanilla HTML + CSS (Tailwind via CDN) + JavaScript
Backend	PHP 8.x
Database	MySQL 8.0
Auth	Google OAuth 2.0 (custom PHP implementation)
BLE	Web Bluetooth API (browser-native)
Charts	Chart.js
Icons	Lucide (via CDN)
Web Server	Apache 2.4 with mod_rewrite
SSL	Let's Encrypt (certbot)

Self-Hosting

Self-hosting for personal, non-commercial use is permitted under the Blue2Scale Source-Available License. Commercial or production deployment requires a commercial license. See LICENSE for details.

Prerequisites

PHP 8.1+ with extensions: pdo_mysql, curl, json, session
MySQL 8.0+
Apache 2.4 with mod_rewrite enabled
HTTPS (Web Bluetooth requires a secure context)

Setup

# Clone the repository
git clone https://github.com/JozefJarosciak/blue2scale.com.git
cd blue2scale.com

# Create and configure the app
cp php/includes/config.example.php php/includes/config.php
# Edit php/includes/config.php with your database credentials and Google OAuth keys

# Import the database schema
mysql -u your_db_user -p your_db_name < php/schema.sql

Apache Virtual Host

Point your Apache DocumentRoot to the php/ subdirectory:

<VirtualHost *:443>
    ServerName your-domain.com
    DocumentRoot /var/www/blue2scale.com/php

    <Directory /var/www/blue2scale.com/php>
        AllowOverride All
        Require all granted
    </Directory>

    # SSL config (certbot will add this)
</VirtualHost>

Enable mod_rewrite:

a2enmod rewrite
systemctl reload apache2

Google OAuth Setup

Go to Google Cloud Console → APIs & Services → Credentials
Create an OAuth 2.0 Client ID (Web application type)
Add your domain to Authorized JavaScript origins: https://your-domain.com
Add the callback URL to Authorized redirect URIs: https://your-domain.com/api/auth/callback
Copy the Client ID and Client Secret into php/includes/config.php

Configuration

Edit php/includes/config.php (copied from config.example.php):

Setting	Description
`SITE_URL`	Full URL of your deployment (no trailing slash)
`DB_HOST`	MySQL hostname (usually `localhost`)
`DB_NAME`	MySQL database name
`DB_USER`	MySQL username
`DB_PASS`	MySQL password
`GOOGLE_CLIENT_ID`	Google OAuth 2.0 client ID
`GOOGLE_CLIENT_SECRET`	Google OAuth 2.0 client secret

Security note: php/includes/config.php is excluded from version control via .gitignore. Never commit it.

Project Structure

blue2scale.com/
├── php/                            # Application root (Apache DocumentRoot)
│   ├── index.php                   # Landing page
│   ├── login.php                   # Login page
│   ├── dashboard.php               # Main dashboard
│   ├── weigh-in.php                # BLE connection + measurement flow
│   ├── history.php                 # Measurement history table
│   ├── charts.php                  # Interactive trend charts
│   ├── goals.php                   # Goal tracking
│   ├── export.php                  # Data export (CSV, JSON)
│   ├── settings.php                # Profile + preferences
│   ├── about.php                   # About page
│   ├── compatibility.php           # Device compatibility list
│   ├── privacy.php                 # Privacy policy
│   ├── .htaccess                   # URL rewriting + security headers
│   ├── api/
│   │   ├── auth/
│   │   │   ├── login.php           # Initiates Google OAuth flow
│   │   │   ├── callback.php        # OAuth callback handler
│   │   │   ├── session.php         # Returns current session info
│   │   │   └── logout.php          # Destroys session
│   │   ├── measurements.php        # GET/POST/DELETE measurements
│   │   ├── goals.php               # GET/POST/DELETE goals
│   │   ├── profile.php             # GET/PUT user profile
│   │   ├── account.php             # DELETE account (permanent)
│   │   ├── device-reports.php      # POST device compatibility reports
│   │   └── export/
│   │       ├── csv.php             # Export measurements as CSV
│   │       └── json.php            # Export measurements as JSON
│   ├── includes/
│   │   ├── config.example.php      # Configuration template (commit this)
│   │   ├── config.php              # Your local config (gitignored)
│   │   ├── db.php                  # PDO database connection
│   │   ├── auth.php                # Session helpers + require_auth()
│   │   ├── functions.php           # Shared utilities
│   │   ├── header.php              # Public page header
│   │   ├── footer.php              # Public page footer
│   │   ├── app-header.php          # App page header (with sidebar)
│   │   └── app-footer.php          # App page footer
│   └── assets/
│       ├── css/                    # Stylesheets
│       └── js/                     # Client-side JavaScript
├── php/schema.sql                  # MySQL schema (import to create tables)
├── LICENSE                         # Source-Available License
├── NOTICE                          # Plain-English license summary
└── README.md                       # This file

API Endpoints

Method	Endpoint	Auth Required	Description
`GET`	`/api/auth/session`	No	Current session info
`GET`	`/api/auth/login`	No	Redirect to Google OAuth
`GET`	`/api/auth/callback`	No	OAuth callback handler
`GET`	`/api/auth/logout`	No	Destroy session
`GET`	`/api/profile`	Yes	Get user profile/preferences
`PUT`	`/api/profile`	Yes	Update user profile/preferences
`GET`	`/api/measurements`	Yes	List measurements (`?limit=N`)
`POST`	`/api/measurements`	Yes	Save a new measurement
`DELETE`	`/api/measurements?id=:id`	Yes	Delete a measurement
`GET`	`/api/goals`	Yes	List goals
`POST`	`/api/goals`	Yes	Create a goal
`DELETE`	`/api/goals?id=:id`	Yes	Delete a goal
`GET`	`/api/export/csv`	Yes	Export measurements as CSV
`GET`	`/api/export/json`	Yes	Export measurements as JSON
`POST`	`/api/device-reports`	No	Submit device compatibility report
`DELETE`	`/api/account`	Yes	Permanently delete account and all data

Contributing

Contributions are welcome for bug fixes and improvements. By submitting a pull request, you agree to assign all rights in your contribution to the project owner (see LICENSE, Section 5).

To contribute:

Fork the repository
Create a feature branch
Make your changes
Submit a pull request with a clear description

Please open an issue first for major changes to discuss the approach.

Security

Self-hosters are responsible for supplying their own credentials. Never commit php/includes/config.php to version control — it contains your database password and OAuth secrets. The file is gitignored by default.

If you discover a security vulnerability, please open a GitHub issue.

License

Blue2Scale is released under the Blue2Scale Source-Available License.

You may view, study, fork, and modify the code for personal, non-commercial, non-production purposes.

Commercial use, production deployment, or incorporation into other products requires a commercial license. To initiate a licensing inquiry, please open a GitHub issue.

See LICENSE for full terms.

Disclaimer

Blue2Scale is an independent project. It is not affiliated with, endorsed by, or associated with Hume Health or any other scale manufacturer. All product names, logos, and trademarks are property of their respective owners.

Blue2Scale is not a medical device. Body composition metrics are estimates based on bioelectrical impedance analysis (BIA) and are provided for informational purposes only. Always consult a healthcare professional for medical advice.

Contact

Website: blue2scale.com
Repository: github.com/JozefJarosciak/blue2scale.com
Issues, bugs, and commercial licensing inquiries: GitHub Issues

Name		Name	Last commit message	Last commit date
Latest commit History 1 Commit
php		php
.gitignore		.gitignore
BLE_SCALE_PROTOCOL.md		BLE_SCALE_PROTOCOL.md
LICENSE		LICENSE
NOTICE		NOTICE
README.md		README.md

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Blue2Scale

What Is Blue2Scale?

Screenshots

Supported Metrics

Core Metrics

Body Fat

Lean & Muscle

Water

Bone & Mineral

Other Composition

Metabolic

Segmental Analysis (5 segments × 3 values = 15 data points)

Tested Devices / Compatibility

Features

Browser Compatibility

How It Works

Tech Stack

Self-Hosting

Prerequisites

Setup

Apache Virtual Host

Google OAuth Setup

Configuration

Project Structure

API Endpoints

Contributing

Security

License

Disclaimer

Contact

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