💳 WalletSimulator

📋 Overview

WalletSimulator is a comprehensive cryptocurrency wallet application that enables users to manage digital assets, perform transactions, and exchange cryptocurrencies. Built with modern web technologies, this full-stack application demonstrates secure user authentication, real-time cryptocurrency price integration via CoinRanking API, and peer-to-peer cryptocurrency transfers.

🛠️ Technologies Used

Backend

• Node.js (v14+) - JavaScript runtime environment
• Express.js - Web application framework
• MongoDB - NoSQL database for data persistence
• Mongoose - MongoDB object modeling
• bcryptjs - Password hashing and encryption
• JWT (jsonwebtoken) - Secure authentication tokens
• express-session - Session management
• cors - Cross-Origin Resource Sharing
• axios - HTTP client for CoinRanking API integration

Frontend

• Vanilla JavaScript - Client-side logic
• HTML5 - Markup structure
• CSS3 - Styling and responsive design

External APIs

• CoinRanking API - Real-time cryptocurrency prices and data

✨ Features

• 🔐 User Authentication: Secure registration and login with encrypted passwords and JWT tokens
• 👤 User Profile Management: Each user has a unique public address for receiving cryptocurrencies
• 💰 Crypto Portfolio: Add and manage multiple cryptocurrencies in your personal wallet
• 💸 P2P Transfers: Send cryptocurrencies to other users using their public address
• 🔄 Crypto Exchange: Convert between different cryptocurrencies using real-time exchange rates
• 📊 Transaction History: Complete tracking of all transactions (sends, exchanges) with hash generation
• 🔍 Advanced Filtering: Filter transactions by hash, user addresses, symbols, amounts, and dates
• 📈 Real-time Prices: Integration with CoinRanking API for up-to-date cryptocurrency prices
• 🗄️ MongoDB Integration: Reliable data storage and retrieval
• 🔒 Security: Password encryption, JWT authentication, and protected API routes
• 📱 Responsive Design: Works on desktop and mobile devices

📁 Project Structure

WalletSimulator/
├── src/
│   └── backend/
│       ├── config/          # Database and app configuration
│       ├── controllers/     # Request handlers
│       ├── middlewares/     # Authentication and validation
│       ├── models/          # MongoDB schemas
│       │   ├── Cripto.js    # Cryptocurrency holdings model
│       │   ├── Transaction.js # Transaction records model
│       │   └── Users.js     # User accounts model
│       └── routes/          # API endpoints
│           ├── authRoutes.js       # Authentication routes
│           ├── cryptoRoutes.js     # Crypto portfolio management
│           ├── settingsRoutes.js   # User settings
│           ├── transactionRoutes.js # Transactions & transfers
│           └── userRoutes.js       # User management
├── public/
│   └── frontend/
│       ├── css/            # Stylesheets
│       ├── html/           # HTML pages
│       │   ├── login.html     # Login/Register page
│       │   └── portfolio.html # Main portfolio dashboard
│       └── js/             # Client-side JavaScript
├── config/                 # Configuration files
└── package.json           # Dependencies and scripts

🚀 Installation

Prerequisites

• Node.js (v14 or higher)
• MongoDB (local or cloud instance)
• npm or yarn package manager
• CoinRanking API Key (get one at coinranking.com)

Setup Instructions

1. Clone the repository

git clone https://github.com/Phosky71/WalletSimulator.git
cd WalletSimulator

2. Install dependencies

cd src/backend
npm install

3. Configure environment variables Create a .env file in the src/backend directory:

PORT=3000
MONGODB_URI=your_mongodb_connection_string
JWT_SECRET=your_secret_key
SESSION_SECRET=your_session_secret
COINRANKING_API_KEY=your_coinranking_api_key

4. Start MongoDB Make sure your MongoDB instance is running.

5. Run the application

npm start

6. Access the application Open your browser and navigate to http://localhost:3000

🔌 API Endpoints

Authentication Routes

• POST /api/auth/register - Register new user
• POST /api/auth/login - User login
• DELETE /api/auth/delete - Delete user account

Cryptocurrency Portfolio Routes

• GET /api/crypto - Get user's crypto portfolio
• POST /api/crypto - Add cryptocurrency to portfolio
• GET /api/crypto/cryptocurrencies - Get list of available cryptocurrencies from CoinRanking
• GET /api/crypto/cryptocurrencies/:uid - Get specific cryptocurrency info
• POST /api/crypto/cryptocurrencies - Get crypto info by UID

Transaction Routes

• GET /api/transactions - Get user's transaction history
• POST /api/transactions/exchange - Calculate exchange rate between cryptocurrencies
• POST /api/transactions/confirm - Confirm and execute crypto exchange
• POST /api/transactions/send - Send cryptocurrency to another user
• GET /api/transactions/user-transactions - Get filtered transactions with advanced search options

User Routes

• GET /api/users - Get user information
• DELETE /api/users - Delete user account

🎯 Key Functionalities

Peer-to-Peer Transfers

Users can send cryptocurrencies to other users by providing:

• Receiver's public address
• Cryptocurrency UID and symbol
• Amount to send

The system validates sufficient balance, updates both sender and receiver portfolios, and generates a unique hash for each transaction.

Cryptocurrency Exchange

Users can exchange between different cryptocurrencies:

1. Select source and target cryptocurrencies
2. Enter amount to exchange
3. System fetches real-time exchange rates from CoinRanking API
4. Confirm exchange to update portfolio
5. Transaction is recorded with unique hash

Transaction Filtering

Advanced filtering options include:

• Hash: Search by transaction hash (partial match)
• User From/To: Filter by sender/receiver public address
• Symbol: Filter by cryptocurrency symbol
• Amount: Filter by minimum amount (from/to)
• Date: Filter by specific date
• Type: Filter by transaction type (send/exchange)

🎓 Learning Objectives

This project demonstrates:

• Full-stack JavaScript development with Node.js and Express
• RESTful API design and implementation
• External API integration (CoinRanking)
• Secure authentication with JWT tokens
• MongoDB database design and relationships
• User-to-user transaction systems
• Real-time data fetching and processing
• Frontend-backend communication
• Session management techniques
• Transaction hash generation using crypto module
• Advanced database querying and filtering

🔐 Security Considerations

• Passwords are hashed using bcrypt before storage
• JWT tokens for stateless authentication
• Protected routes require valid authentication
• Input validation on all endpoints using express-validator
• CORS configuration for secure cross-origin requests
• Unique transaction hashes using SHA-256
• Atomic database operations to prevent race conditions
• Balance validation before executing transfers

📝 Models

User Model

• Username, email, password (hashed)
• Public address (unique identifier for receiving funds)
• Timestamps

Crypto Model

• User reference
• Cryptocurrency UID, name, symbol
• Amount held
• Timestamps

Transaction Model

• Unique hash (SHA-256)
• User From/To references
• Symbol, from/to amounts
• Transaction type (send/exchange)
• Date timestamp

🚧 Future Enhancements

• Add transaction categories and tags
• Implement email notifications for transactions
• Create admin dashboard for system monitoring
• Implement two-factor authentication
• Add support for more cryptocurrency APIs
• Implement transaction limits and daily caps
• Add multi-signature wallet support

👨‍💻 Author

Antonio Juan González-Conde Abril (Phosky71)

• GitHub: @Phosky71

📄 License

This project is part of a portfolio demonstrating full-stack development capabilities.

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This is an educational project created to demonstrate full-stack web development skills with Node.js, Express, MongoDB, vanilla JavaScript, and external API integration.