🏦 EliteBank - Secure Transaction System

A modern, full-stack MERN application designed for high-performance, secure banking transactions.

Features • Tech Stack • Architecture • Getting Started

---

✨ Features

• 🔐 Secure Transactions: All money transfers require a mandatory, hashed 4-digit PIN verification.
• 📜 Atomic Ledger: A dual-entry ledger system ensures transaction integrity even in standalone MongoDB environments.
• ⚡ Real-time Updates: Instant balance updates and transaction history tracking.
• 🎨 Premium UI/UX: A modern, responsive dashboard built with React, Tailwind CSS, and Lucide React icons.
• 🛡️ Robust Security: JWT-based authentication stored securely, with password hashing (Bcrypt) and payload validation (Joi).
• 🛠️ Developer Ready: Fully Docker-ready, automated monorepo build scripts, and production-optimized routing.

---

🛠 Tech Stack

💻 Frontend (Client)

• React 18 — Fast, modern UI development.
• Tailwind CSS — Utility-first styling for a premium aesthetic.
• React Router v6 — Declarative routing and navigation.
• Axios & Context API — API communication and global state management for auth & transactions.

⚙️ Backend (API Server)

• Node.js & Express.js (v5) — Robust backend framework.
• MongoDB & Mongoose — Database for flexible user, account, and ledger storage.
• Redis (Upstash) — Fast token blacklisting and session management.
• JWT & Bcrypt — Secure user authentication and password/PIN protection.

---

🏗 Architecture

EliteBank leverages a scalable MERN architecture with a focus on transaction integrity and security:

┌──────────────────────────────────────────────────────────────────┐
│                        CLIENT (React 18)                        │
│   Context API manages Auth & Transaction states globally         │
└──────────┬────────────────────────────┬─────────────────────────┘
           │ HTTP (RESTful API)         │ 
           ▼                            ▼
┌───────────────────────┐    ┌────────────────────────────────────┐
│   EXPRESS API SERVER  │    │           REDIS (Upstash)          │
│   (Node.js / Express) │───>│  (Fast Token Blacklisting &        │
│                       │    │   Session Management)              │
│  • JWT Verification   │    └────────────────────────────────────┘
│  • Input Validation   │
│  • Ledger Processing  │
└──────────┬────────────┘
           │ 
           ▼
┌───────────────────────┐
│   MONGODB CLUSTER     │
│  (Users, Accounts,    │
│   Ledger Entries)     │
└───────────────────────┘

Key Design Decisions

1. Dual-Entry Ledger: Instead of simply updating a balance field, every transaction creates two immutable ledger entries (Debit and Credit). The current balance is calculated dynamically on-the-fly via MongoDB aggregation, guaranteeing absolute data integrity.
2. Lazy Account Initialization: Bank accounts are automatically generated upon registration or upon the first login, ensuring users never encounter an "Account Not Found" error.
3. Monorepo Structure: A single root package.json seamlessly manages dependencies and build scripts for both the frontend and backend, enabling easy 1-click deployments on platforms like Render.

---

🚀 Getting Started

Follow these instructions to get a copy of the project up and running on your local machine.

Prerequisites

• Node.js (v18+)
• MongoDB URI (Local or MongoDB Atlas)
• Redis URL (Local or Upstash)

1. Clone & Install

git clone https://github.com/your-username/bank-system.git
cd bank-system

# Install dependencies for BOTH frontend and backend automatically
npm run install-all

2. Environment Variables

Create a .env file in the backend directory:

PORT=5000
NODE_ENV=development
MONGODB_URI=your_mongodb_connection_string
JWT_SECRET=your_jwt_secret_key
REDIS_URL=your_redis_url

3. Running the Application

Because this is a monorepo, you can start both servers concurrently with a single command from the root folder:

# Starts Express on Port 5000 and React on Port 3000
npm run dev

Visit http://localhost:3000 to access the EliteBank dashboard!

---

🚢 Deployment (Render)

This project is fully optimized for Render using a single-service architecture (the backend serves the frontend in production).

1. Build Command: npm run build
2. Start Command: npm start
3. Environment Variables: Add MONGODB_URI, REDIS_URL, JWT_SECRET, and NODE_ENV=production in the Render dashboard.

---

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.