Subsync - Smart Subscription & Recurring Expense Management SaaS 🔄📊

Subsync is an automated, enterprise-grade subscription and recurring expense management platform. It pairs a Java 21 / Spring Boot 3.2 backend with a cross-platform Flutter mobile application to give users intelligent financial insights, automated bank transaction pattern recognition, scheduled billing alerts, and downloadable invoice/PDF statements.

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🏛️ Architecture & System Design

graph TD
    Mobile[Flutter Mobile Client] -->|REST API / JWT| Backend[Spring Boot 3 Backend API]

    subgraph Core Modules
        Backend --> SubEngine[Subscription Engine: Pattern Detection]
        Backend --> Scheduler[Sync Scheduler & Reminders]
        Backend --> Invoicing[Invoice & PDF Generation]
        Backend --> BankModule[Bank Transaction Sync]
    end

    Backend --> Postgres[(PostgreSQL Database)]

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✨ Key Features

1. 🧠 Intelligent Subscription Detection (SubscriptionEngine)

• Transaction Pattern Recognition: Analyzes historical bank transactions by merchant groupings and interval deltas.
• Auto-Cycle Identification: Automatically categorizes billing intervals (Weekly: 7-day delta, Monthly: 30-day delta, Yearly: 365-day delta).
• Next Billing Date Forecasting: Accurately projects future charge dates to prevent unexpected renewals.

2. 📱 Modern Flutter Mobile Client

• State Management: Clean GetX architecture with reactive controllers and route bindings.
• Networking: Robust HTTP client integration via Dio with global interceptors.
• Reports & Documents: In-app PDF viewer integration for financial statements and invoices.
• Social Authentication: Seamless Google Sign-In and secure token storage with GetStorage.

3. 📑 Financial Reporting & Invoices

• Generates downloadable invoice records and financial summaries.
• Detailed spending breakdown categorized by entertainment, utilities, SaaS services, and business tools.

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📂 Repository Structure

Subsync/
├── subsync_backend/         # Spring Boot 3.2 REST API (Java 21)
│   ├── src/main/java/com/rseelabs/subsync/
│   │   ├── core/           # Security, exceptions, global config
│   │   └── modules/
│   │       ├── auth/       # JWT authentication & registration
│   │       ├── bank/       # Bank account linking & transaction ingestion
│   │       ├── dashboard/  # Aggregated metrics & graphs
│   │       ├── report/     # PDF generation & spending summaries
│   │       └── subscription/# SubscriptionEngine & SyncScheduler
│   └── pom.xml             # Maven dependencies
│
└── subsync_app/             # Flutter Mobile Application
    ├── lib/                # GetX controllers, views & repositories
    └── pubspec.yaml        # Flutter dependencies

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🚀 Quickstart

Backend

cd subsync_backend
./mvnw spring-boot:run

Mobile App

cd subsync_app
flutter pub get
flutter run