Toolbox — Android Utility App

A privacy-respecting, offline-first Android utility app with 25+ tools across measurement, conversion, and everyday use. Built with Kotlin + Jetpack Compose + Material 3.

Features

Measurement

Tool	Description
Bubble Level	Circular + linear level with pitch/roll readout
Compass	Compass rose with magnetic/true north toggle
Protractor	On-screen angle measurement
Sound Meter	Live dB meter with min/avg/max stats
Ruler	Full-width ruler with cm/in toggle and credit-card calibration
Light Meter	Ambient lux sensor readout
Barometer	Atmospheric pressure via pressure sensor
Altitude	Elevation estimate from barometric pressure
Gyroscope	Real-time angular velocity on all three axes
Humidity	Relative humidity (on supported hardware)
Metal Detector	Magnetic field strength as a proximity indicator
Speedometer	GPS-based speed with unit toggle
Vibrometer	Vibration intensity from accelerometer
Spectrum Analyzer	Real-time audio frequency spectrum via FFT

Conversion

Tool	Description
Unit Converter	10+ categories — length, weight, temperature, volume, and more
Percentage Calculator	Percent of, percent change, and reverse calculations
Tip Calculator	Bill splitting with custom tip %
Number Base	Convert between binary, octal, decimal, and hex

Everyday

Tool	Description
QR Scanner	Scan barcodes/QR codes and generate QR codes from text
Counter	Persistent multi-step counter with DataStore persistence
Stopwatch & Timer	Stopwatch with laps; countdown timer with background notification
Random	Dice rolls, coin flip, and random number generator
Color Picker	Sample any color from the camera feed
Magnifier	Camera-based magnifier with zoom control
Mirror	Front camera as a mirror
Heart Rate	Estimate BPM via rear camera finger placement

Other

Tool	Description
Flashlight	Torch with brightness control, SOS mode, and strobe
Pedometer	Step counter using the hardware step sensor

Platform Features

• Quick Settings Tiles — Flashlight, Sound Meter, Bubble Level, and Timer directly from the notification shade
• App Shortcuts — Jump to frequently used tools from the launcher long-press menu
• Favorites — Pin any tool to a customizable favorites screen
• Share Measurements — Export a measurement card image from any sensor tool
• Dynamic theming — Material You color system on Android 12+, static fallback on older devices
• Predictive back — Full support for Android 14 predictive back gesture

Tech Stack

• Language: Kotlin 2.0+
• UI: Jetpack Compose + Material 3
• Navigation: Type-safe Navigation Compose 2.8+ (@Serializable routes)
• Camera: CameraX 1.6+ with camera-compose viewfinder
• QR: ZXing core 3.5.3 (custom ImageAnalysis.Analyzer, no external Activity)
• Persistence: DataStore Preferences (counter state, favorites, theme)
• Timer: AlarmManager.setExactAndAllowWhileIdle() + foreground service for live notification
• Sensors: DisposableEffect + LifecycleEventObserver with low-pass filtering
• Min SDK: 26 (Android 8.0) · Target SDK: 36

Architecture

Single-module, package-per-feature layout. No DI framework — manual ViewModelProvider.Factory injection kept simple for MVP scale.

app/
├── core/          # Shared — sensors, camera, permissions, UI components, sharing
├── dashboard/     # Home screen grid with search
├── measurement/   # Sensor-based measurement tools
├── conversion/    # Unit/math conversion tools
├── everyday/      # Camera and general-purpose tools
├── lighting/      # Flashlight
├── motion/        # Pedometer
├── favorites/     # Pinned tools screen
├── settings/      # Theme + preferences
├── tiles/         # Quick Settings tile services
└── nav/           # Navigation destinations

Building

# Debug build
./gradlew assembleDebug

# Release build (requires signing config)
./gradlew assembleRelease

Requires Android Studio Meerkat or newer, JDK 21.

Privacy

• No analytics, no crash reporting, no ads
• No network requests — fully offline
• Runtime permissions are requested lazily, only when the relevant tool is opened
• All sensor data stays on-device

License

MIT