Track your caffeine. Protect your sleep.
Caffeine Health is a beautifully designed Android app that helps you understand how your caffeine intake affects your body throughout the day — and whether that late-afternoon espresso might cost you sleep tonight.
Log drinks from a curated catalog, watch your active caffeine level in real time on a 24-hour curve, and get a personalized sleep forecast based on your unique metabolism.
 Onboarding |
 Profile Ready |
 Dashboard |
 Source Analytics |
- Live caffeine curve — a smooth 24-hour chart showing your active caffeine level, updated in real time
- Emoji markers — each logged drink appears on the chart with its emoji for quick visual reference
- Sleep forecast — see how much caffeine will still be active at your bedtime and whether it crosses your safe threshold
- Today's total — at-a-glance milligram count for everything consumed today
- Drink detail sheet — tap any logged drink to see its contribution curve, peak level, current level, and total impact over time
- Quick actions — edit, duplicate, or delete entries directly from the detail sheet
- Curated drink database — browse drinks across categories like coffee, tea, energy drinks, soda, and more
- Search & filter — Material 3 search bar with expressive category filter chips
- One-tap logging — log a drink with a single tap and get snackbar confirmation
- Custom serving sizes — adjust caffeine amount and timing before logging
- Guided profiling flow — set your age range, weight, bedtime, sleep sensitivity, lifestyle factors, and relevant medications
- Pharmacokinetic modeling — the app calculates a personalized caffeine half-life based on real-world factors (smoking, alcohol, CYP1A2 inhibitors)
- Science-backed sources — every lifestyle adjustment links to its pharmacological source
- Skip-friendly — sensible defaults if you prefer to get started immediately
- Half-life tuning — fine-tune your caffeine metabolism rate
- Bedtime configuration — set your typical sleep time for accurate forecasts
- Sleep threshold — define the milligram level you consider safe before bed
- Appearance — theme and display preferences
- Date & time format — 12-hour / 24-hour clock, date format customization
com.uc.caffeine
├── MainActivity.kt # Root scaffold, bottom nav, Navigation 3
├── MainNavigation.kt # Navigation destinations
├── data/
│ ├── model/ # Room entities (DrinkPreset, ConsumptionEntry, DrinkUnit)
│ ├── dao/ # Room DAOs
│ ├── CaffeineDatabase.kt # Room database with JSON preset seeding
│ ├── SettingsRepository.kt # DataStore-backed user preferences
│ └── UserSettings.kt # Settings data class
├── ui/
│ ├── screens/
│ │ ├── HomeScreen.kt # Dashboard with chart, sleep forecast, log
│ │ ├── AddScreen.kt # Drink catalog with search & filter
│ │ └── settings/ # Settings sub-screens (appearance, profile, etc.)
│ ├── components/ # Reusable UI: chart, scaffold, haptics, shimmer
│ ├── onboarding/ # Multi-step profiling flow
│ ├── theme/ # Material 3 color scheme, Montserrat typography
│ └── viewmodel/ # Shared CaffeineViewModel (MVVM)
└── util/
├── CaffeineCalculator.kt # One-compartment pharmacokinetic model
├── ChartDataGenerator.kt # 24-hour curve + contribution chart data
└── CategoryUtils.kt # Drink category helpers & icons
The app follows a single-activity MVVM pattern:
| Layer | Responsibility |
|---|---|
| View | Jetpack Compose screens + reusable components |
| ViewModel | CaffeineViewModel — shared state, actions, caffeine math orchestration |
| Data | Room database for drinks & entries, DataStore for user settings |
| Util | Pure calculation logic (pharmacokinetics, chart data generation) |
| Component | Technology |
|---|---|
| Language | Kotlin |
| UI Framework | Jetpack Compose |
| Design System | Material 3 with Expressive motion |
| Navigation | Navigation 3 |
| Local Database | Room |
| Preferences | DataStore |
| Charts | Vico (Compose + M3 theming) |
| Image Loading | Coil 3 |
| Typography | Montserrat (Google Fonts) |
| Min SDK | 31 (Android 12) |
| Target SDK | 36 |
The app uses a one-compartment oral pharmacokinetic model:
- Absorption phase — linear ramp from ingestion to peak based on drink-specific absorption rate
- Elimination phase — exponential decay governed by your personal half-life setting
- Half-life personalization — computed from age, weight, smoking, alcohol, liver health, and CYP1A2-inhibiting medications during onboarding
This keeps the curve and sleep forecast grounded in real pharmacology while remaining practical for daily use.
- Android Studio Ladybug (2024.3) or newer
- JDK 11+
- Android SDK 36 installed via SDK Manager
# Clone the repository
git clone https://github.com/ohuc/CaffeineHealth.git
cd CaffeineHealth
# Open in Android Studio and sync Gradle, or build from CLI:
./gradlew assembleDebug
# Install on a connected device / emulator:
./gradlew installDebugNote: The app requires Android 12 (API 31) or higher.
compileSdktargets API 36 — use an emulator with API 31+ to run it.
CaffeineHealth/
├── app/ # Main application module
│ ├── src/main/
│ │ ├── assets/ # Drink preset JSON database
│ │ ├── java/ # Kotlin source code
│ │ └── res/ # Resources (drawables, fonts, values)
│ └── build.gradle.kts # App-level dependencies
├── build.gradle.kts # Project-level config
├── settings.gradle.kts # Module includes
└── gradle/ # Gradle wrapper & version catalog
Caffeine Health is built with Material 3 Expressive principles:
- Dynamic Color — adapts to your device wallpaper on Android 12+ with a curated espresso-toned fallback palette
- Expressive Motion —
MotionScheme.expressive()for fluid, personality-rich transitions - Montserrat typography — clean, modern font family throughout the entire app
- Haptic feedback — tactile responses on key interactions across dashboard, catalog, and settings
- Dark mode — full dark theme support with carefully tuned surface/container colors
Contributions are welcome! Here's how to get started:
- Fork the repository
- Create a feature branch:
git checkout -b feature/amazing-feature - Commit your changes:
git commit -m 'Add amazing feature' - Push to the branch:
git push origin feature/amazing-feature - Open a Pull Request
- Follow existing code style and architecture patterns
- Keep the shared ViewModel pattern — avoid per-screen ViewModels unless there's a strong reason
- Use Material 3 components and the app's existing design tokens
- Test on API 31+ emulator before submitting
This project is licensed under the GNU General Public License v3.0 — see the LICENSE file for details.
- Vico — beautiful charting library for Compose
- Coil — fast image loading for Kotlin
- Material 3 — Google's latest design system
- Montserrat — typeface by Julieta Ulanovsky
Made with ☕ and Kotlin