MatCal

A minimalist calendar for Android.

Recently I switched to GrapheneOS as my main mobile OS. And as it turns out, it does not ship with a built-in calendar app. So I created MatCal as both, a personal learning project and a practical solution.

The goal is to provide a lightweight, functional, and system-native calendar experience without compromising privacy.

Features

• Event Management: Create, view and manage events
• Offline first: All data is stored locally using SQLite (Room)
• iCal Sync: Import and sync external calendars (University, Work, Holidays) via URL
• No Bloat: No ads, no tracking, no unneeded permissions

Privacy

• Events are stored locally in an embedded SQLite database managed through Room.
• MatCal includes no trackers, analytics, or background data collection.
• android.permission.INTERNET is only used when you explicitly add or refresh an iCal subscription URL

Design

MatCal utilizes the system's Dynamic Colors, adapting automatically to your wallpaper and system theme (light/dark mode)

Screenshots

Calendar (Dark Theme / Black background)

Calendar (Light Theme / Red background)

(WIP)

Requirements

• Recommended: Android 12+ (API 31) for full Dynamic Color support.
• Tested Environment: Google Pixel 9a running GrapheneOS (Android 16, API 36).

Download

You can grab the latest APK from the Releases Page.

Tech Stack

• Language: Kotlin
• UI: Jetpack Compose & Material 3
• Database: Room.
• Libraries:
  • Biweekly: Parsing iCalendar (.ics)
  • Calendar Compose: The core Compose calendar component
  • AboutLibraries: Automatic open-source license attribution.

Contributing

MatCal is a learning-focused project and contributions are appreciated!

If you find a bug or have an idea for improvement, feel free to open an issue or submit a pull request.

License

Distributed under MIT License. See LICENSE for more information.