FinSync: Modern Microservices Expense Management Platform

FinSync is a high-performance, scalable expense management platform built on a modern microservices architecture. It enables users to track personal finances, manage group expenses, and automate complex debt settlements with a seamless, real-time experience.

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🏗️ Architecture Overview

FinSync leverages an event-driven microservices architecture to ensure high availability, scalability, and loose coupling between components.

graph TD
    Client[Next.js Frontend] <--> Gateway[API Gateway]

    subgraph "Microservices"
        Gateway <--> Auth[Auth Service]
        Gateway <--> Group[Group Service]
        Gateway <--> Settlement[Settlement Service]
        Gateway <--> Personal[Personal Finance Service]
    end

    subgraph "Infrastructure"
        Auth -- "user-registered-topic" --> Kafka((Kafka))
        Kafka -- "User Events" --> Group
        Kafka -- "User Events" --> Personal

        Group -- "group-expense-created-topic" --> Kafka
        Kafka -- "Expense Events" --> Settlement

        Group --- DBG[(PostgreSQL - Group)]
        Auth --- DBA[(PostgreSQL - Auth)]
        Settlement --- DBS[(PostgreSQL - Settlement)]
        Personal --- DBP[(PostgreSQL - Personal)]
    end

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🚀 Key Features

• 🔐 Unified Authentication: Secure JWT-based authentication with role-based access control.
• 👥 Collaborative Group Expenses: Create groups, invite members, and split expenses effortlessly.
• ⚖️ Automated Settlements: Advanced algorithms to simplify debts and generate optimal settlement plans.
• 📊 Personal Finance Insights: Detailed analytics, budgeting tools, and transaction categorization.
• ⚡ Real-time Event Synchronization: Asynchronous service communication via Kafka for decoupled data handling.
• 🎨 Premium UI/UX: Dark-mode first design with smooth animations and responsive layouts.

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🛠️ Tech Stack

Backend (Microservices)

• Language: Java 21
• Framework: Spring Boot (3.3.5 / 4.0.3)
• Security: Spring Security + JWT
• Gateway: Spring Cloud Gateway
• Persistence: Spring Data JPA / Hibernate
• Database: PostgreSQL 15
• Messaging: Apache Kafka (Event-driven architecture)
• Mapping: MapStruct for high-performance DTO mapping
• Utils: Lombok, Jackson

Frontend

• Framework: Next.js 14 (App Router)
• Library: React 18
• Language: TypeScript
• Styling: Tailwind CSS
• State Management: Zustand
• Data Fetching: TanStack Query (React Query)
• Components: Radix UI, Lucide Icons
• Animations: Framer Motion
• Visualizations: Recharts

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📂 Service Breakdown

Service	Responsibility
API Service	Central entry point, request routing, and JWT validation.
Auth Service	User identity management, registration, and secure authentication.
Group Service	Management of groups, members, and shared expenses.
Settlement Service	Calculation of balances and generation of debt-settlement plans.
Personal Finance	Individual expense tracking, budgeting, and financial analytics.
Common Events	Shared library for event schemas and serializable Kafka payloads.

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⚙️ Getting Started

Prerequisites

• JDK 21+
• Node.js 18+
• Docker & Docker Compose
• Maven 3.9+

Installation

1. Clone the repository:

   git clone https://github.com/Adipatil7/finsync-microservices.git
   cd finsync-microservices

2. Build the Backend:

   # Build the parent and install shared events
   cd common-events && mvn clean install
   cd ..
   # Build individual services (optional, docker-compose will handle this)

3. Install Frontend Dependencies:

   cd finsync-frontend
   npm install

Running with Docker

The easiest way to start the entire platform is using Docker Compose:

cd Infrastructure
docker-compose up -d

This will spin up:

• 4 PostgreSQL instances (Auth, Group, Settlement, Personal)
• Kafka & Zookeeper/KRaft cluster
• All Backend Microservices
• API Gateway

The services will be available at http://localhost:8080.

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📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

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Created with me.