Material Syncthing: A modern, beautiful Android client for Syncthing

Thanks for the great work regarding the UI @lostf1sh. The main goal of this fork is to provide a more stable and reliable experience for users, while also adding new features and enhancements.

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What is this?

Syncthing is a free, open-source, peer-to-peer file synchronization tool that allows you to sync files between all your devices without relying on cloud services. This works especially well for Obsidian Notes, Photos and Videos, Emulator Game Saves etc. It is cross-platform and works on Windows, macOS, Linux, Android, and more.

Material Syncthing is a ground-up rebuild of the Syncthing Android client, written in Kotlin with Jetpack Compose and Material 3 Expressive. It replaces the legacy View/XML UI with a modern, fluid interface built for Android 9+.

Originally ported from Catfriend1/syncthing-android, this project strips away the Java/XML legacy in favor of coroutines, Flow, and Compose — end to end.

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Download

The Obtainium button imports the app and its release settings for automatic updates. If you want to build from source, see the Build section below.

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Features

🎨Material 3 Expressive	Wavy progress indicators, expressive motion, flexible top app bars, spring animations
📁Folder Management	Create, edit, browse, pause/resume, repair index, ignore patterns
📱Device Management	Add via ID or QR scan, share existing folders, connection status
🔄Real-time Sync	ForegrounddataSync service with persistent notification, boot-on-start
📊Insights Dashboard	Bandwidth history, sync health, recent changes, conflict resolution
🔔Smart Notifications	Error center, device connection alerts, sync completion
🔒Privacy First	No analytics, no cloud — your data stays on your devices
🌙Dynamic Color	Full Material You dynamic theming on Android 12+

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Tech Stack

Layer	Tech
UI	Jetpack Compose + Material 3 Expressive (1.5.0-alpha17)
Architecture	Coroutines + Flow,StateFlow for UI state, SharedFlow for events
Networking	Ktor client + OkHttp + kotlinx.serialization
DI	Manual composition (AppContainer) — no framework overhead
Persistence	DataStore (preferences), Room-ready architecture
Native	Embedded syncthing binary launched via ProcessBuilder
Build	Gradle 9.x, Kotlin 2.2.10, Version Catalogs

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Architecture

┌─────────────┐     ┌──────────────┐     ┌─────────────┐
│     app     │────▶│   ui-core    │────▶│  core-api   │
│  (Screens)  │     │(Theme/Design)│     │(REST Client)│
└──────┬──────┘     └──────────────┘     └──────┬──────┘
       │                                          │
       ▼                                          ▼
┌──────────────┐     ┌──────────────┐     ┌─────────────┐
│    data      │◀────│AppContainer  │◀────│core-service │
│(Repo/Settings)│     │ (State Hub)  │     │(Foreground) │
└──────────────┘     └──────────────┘     └─────────────┘
                            │
                            ▼
                     ┌──────────────┐
                     │  core-native │
                     │(Binary Launch)│
                     └──────────────┘

• Coroutines + Flow end to end. No AIDL, no listener callbacks.
• StateFlow shared via AppContainer singleton — tiles and UI read the same flows.
• Cancellation-safe — every suspend handler rethrows CancellationException.

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Build

Debug APK:

./gradlew :app:assembleDebug

Release APK:

./gradlew :app:assembleRelease

Install:

./gradlew :app:installDebug

Run tests:

./gradlew test

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Modules

Module	Purpose
app	Activity, navigation, screen composables, DI wiring
core-native	Native binary launcher, config bootstrapper, run state
core-service	Foreground service, notifications, boot receiver
core-api	Ktor REST client, event stream parser, DTOs
data	DataStore settings, repositories, sync constraints, health
ui-core	Shared Compose theme (SyncthingTheme), expressive components, formatters

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Requirements

• Android 9 (API 28) or higher
• Target SDK 35, Compile SDK 36
• JDK 17

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Permissions

• INTERNET — Syncthing REST API
• FOREGROUND_SERVICE_DATA_SYNC — Persistent sync service
• POST_NOTIFICATIONS — Service state and error notifications
• RECEIVE_BOOT_COMPLETED — Auto-start on boot
• CAMERA — QR code scanning
• MANAGE_EXTERNAL_STORAGE (API 30+) — Folder access

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Known follow-up work

• Configuration backups restore app preferences, folders, devices, and Syncthing options on the same device. Device identity (cert.pem / key.pem) migration is intentionally not implemented.
• Android cloud document providers do not expose filesystem paths usable by the native Syncthing process. Primary storage and UUID-based removable volumes are supported; virtual providers would require a separate copy/cache layer.
• External file versioning requires an executable command supplied by the user and still needs device-specific validation on Android.

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License

MPL-2.0. See NOTICE for upstream attribution.

This project is a derivative of Catfriend1/syncthing-android and fork of lostf1sh/material-syncthing, rebuilt with Compose and modern Android architecture.