CashGrid — Full-Stack Commercial Cash Payment Platform

A production-grade, full-stack financial operations platform. Featuring a modern Next.js frontend and a robust Spring Boot backend, built to manage commercial money flows with high security and auditability.

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📸 Visual Tour

📊 Dashboard Overview

Centralized view of system status, user roles, and quick actions.

💸 Payments & Details

Modern payment table with the new Transaction Details Pane showing full audit history.

📝 Audit Logs

Detailed, tamper-proof logs capture every significant action in the system. Each audit entry records the user, timestamp, action type, and affected entities, ensuring full traceability for compliance and security reviews.

👤 Profile & Security

Comprehensive account management for updating credentials and preferences.

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🛠 Tech Stack

💻 Frontend

• Framework: Next.js 15 (App Router)
• Styling: Tailwind CSS 4 (Modern utility-first CSS)
• UI Components: Shadcn UI (Radix UI Primitives)
• State Management: Zustand
• Data Fetching: TanStack Query v5 (React Query)
• Forms: React Hook Form + Zod Validation
• Icons: Lucide React

⚙️ Backend

• Language: Java 21
• Framework: Spring Boot 4.0.2
• Security: Spring Security + JWT (jjwt)
• Database: PostgreSQL 18 + Flyway Migrations
• API Docs: Swagger UI (springdoc-openapi)
• Rate Limiting: Bucket4j

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🚀 Quick Start (Docker)

The easiest way to run the entire stack (Frontend, Backend, and Database) is using Docker Compose.

docker compose up --build

• Frontend: http://localhost:3000
• Backend API: http://localhost:8080
• Swagger UI: http://localhost:8080/swagger-ui.html

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🏗 Architecture & Features

Key Modules

• Auth Module: Secure JWT-based authentication with Login, Register, and Token Refresh.
• Account Module: Management of bank accounts with TR Mod-97 IBAN validation.
• Payment Module: Maker-Checker workflow ensuring no single point of failure for transactions.
• Limit Module: Dynamic transaction limits configured per role and currency.
• Audit Module: Immutable event sourcing for every payment state change.

Highlights

• Maker-Checker Process: Payments created by a MAKER must be approved by a CHECKER.
• Idempotency: Prevents duplicate payments using unique reference keys.
• Real-time Validation: Frontend and Backend Zod/Jakarta validation for data integrity.
• Profile Management: Users can securely update their username, email, and password.
• Modern UI: Sleek, responsive interface with Dark/Light mode support.

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📡 API Overview

Authentication & Profile

Method	Endpoint	Description	Access
POST	/api/v1/auth/login	Authenticate & get tokens	Public
PATCH	/api/v1/auth/me/username	Update display name	Authenticated
PATCH	/api/v1/auth/me/email	Update contact email	Authenticated
PUT	/api/v1/auth/me/password	Change security password	Authenticated

Core Operations

Module	Feature	Capability
Accounts	CRUD	Create, Read, Update, and Soft-Delete bank accounts.
Payments	Workflow	Initiate, Approve, Reject, and View detailed transaction logs.
Limits	Controls	Set maximum single and daily limits for roles.
Audit	Compliance	Filter and search through immutable system logs.

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🧪 Testing

Backend Integration Tests

Uses Testcontainers to run 40+ tests against a real PostgreSQL instance.

./gradlew :backend:test

Frontend Linting

cd frontend
npm run lint

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📁 Project Structure

cash-grid/
├── frontend/                # Next.js Application
│   ├── src/app/             # Pages and Layouts
│   ├── src/components/ui/   # Shadcn Components
│   └── src/lib/             # API, Hooks, and Store
├── backend/                 # Spring Boot Application
│   ├── src/main/java/       # Business Logic
│   └── src/test/java/       # Integration Tests
├── docker-compose.yml       # Full-stack Orchestration
└── README.md                # Project Documentation

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📄 License

This project is built for educational and demonstration purposes.