🏦 Bank Simulator

A full-stack banking simulator built to explore real-world backend architecture, secure transaction handling, and modern web development.

🚀 Overview

Bank Simulator is a project focused on simulating core banking operations such as account management, transactions, and asset handling, while applying production-level design decisions.

The system emphasizes:

• Data consistency
• Security
• Clean architecture
• Test-driven development

🧠 Backend

Built with Java + Spring, following a layered architecture (Clean Architecture inspired):

🔹 Architecture

• Application Layer (Use Cases)
• Domain Layer (Business Rules)
• Infrastructure Layer (DB, Security, External Services)

🔹 Key Features

• 💳 Account & Client Management
• 💸 Transaction system with ACID guarantees
• 🔐 Custom token-based authentication
• 🔑 RSA cryptography per account
  • Public key stored in DB
  • Private key stored securely (file/memory)
• 📩 Email verification & password reset flows
• 🌐 Google OAuth login

🔹 Database

• PostgreSQL (production-like environment)
• H2 (for automated tests)
• JDBC (no ORM, full control over queries)

🔹 Testing

• ✅ Test-Driven Development (TDD)
• Automated tests using H2 in-memory database

🎨 Frontend

Built with React + TypeScript

🔹 Features

• Authentication (JWT-based)
• Account dashboard
• Balance & transactions visualization
• Asset marketplace interface
• Integration with backend APIs

☁️ Infrastructure

• AWS (deployment & backend services)
• AWS Secrets Manager (secure credentials)
• HTTPS-enabled APIs
• Integration with external services (e.g. Ko-fi webhooks)

🔐 Security Highlights

• Token-based authentication
• Cryptographic signing of transactions
• Secure key management
• Validation layers across the system

📦 Project Purpose

This project was built as a learning and portfolio project, aiming to simulate how real banking systems are designed, focusing on:

• Backend engineering best practices
• System design
• Security fundamentals
• Real-world trade-offs

🛠️ Tech Stack

Backend

• Java
• Spring Framework
• JDBC

Frontend

• React
• TypeScript

Database

• PostgreSQL
• H2

Infrastructure

• AWS

📌 Future Improvements

• Real-time transactions (WebSockets)
• Better asset trading engine
• Rate limiting & fraud detection
• Observability (logs, metrics, tracing)

📄 License

This project is licensed under the MIT License.

You are free to use, modify, and distribute this project, as long as proper credit is given.

🤝 Usage

Feel free to use this project for learning, personal, or commercial purposes.

If you use this project, please give proper credit by referencing this repository.

👨‍💻 Author

Developed by Alessandro Bezerra