Web3 Backend API

A robust Node.js Express backend for Web3 applications with MongoDB integration, supporting multiple blockchain networks (Ethereum, Polygon, BSC).

Features

• 🔐 JWT Authentication & Wallet-based Authentication
• 🌐 Multi-network support (Ethereum, Polygon, BSC)
• 💾 MongoDB integration with Mongoose
• 🔒 Security middleware (Helmet, CORS, Rate limiting)
• ✅ Input validation with express-validator
• 📊 Transaction tracking and wallet management
• 🚀 RESTful API design
• 🧪 Test-ready structure

Tech Stack

• Runtime: Node.js (>=18.0.0)
• Framework: Express.js
• Database: MongoDB with Mongoose
• Blockchain: Web3.js & Ethers.js
• Authentication: JWT & Wallet signatures
• Validation: express-validator
• Security: Helmet, CORS, bcryptjs

Quick Start

Prerequisites

• Node.js (>=18.0.0)
• MongoDB
• npm or yarn

Installation

1. Clone the repository:

git clone <repository-url>
cd backend

2. Install dependencies:

npm install

3. Set up environment variables:

cp .env.example .env
# Edit .env with your configuration

4. Start MongoDB (if running locally):

mongod

5. Run the application:

# Development mode
npm run dev

# Production mode
npm start

The server will start on http://localhost:3000 (or your configured PORT).

Environment Variables

Copy .env.example to .env and configure:

• MONGODB_URI: MongoDB connection string
• JWT_SECRET: Secret key for JWT tokens
• ETHEREUM_RPC_URL: Ethereum RPC endpoint
• POLYGON_RPC_URL: Polygon RPC endpoint
• BSC_RPC_URL: BSC RPC endpoint

API Endpoints

Authentication

• POST /api/auth/register - Register user
• POST /api/auth/login - Login user
• POST /api/auth/wallet-login - Login with wallet signature
• GET /api/auth/me - Get current user
• PUT /api/auth/profile - Update profile

Wallets

• GET /api/wallets - Get user wallets
• POST /api/wallets - Add wallet
• GET /api/wallets/:address - Get wallet details
• GET /api/wallets/:address/balance - Get wallet balance
• GET /api/wallets/:address/transactions - Get wallet transactions

Transactions

• GET /api/transactions - Get transactions
• POST /api/transactions - Create transaction
• GET /api/transactions/:txHash - Get transaction details
• GET /api/transactions/stats - Get transaction statistics

Web3

• GET /api/web3/networks - Get supported networks
• GET /api/web3/gas-price - Get current gas price
• POST /api/web3/estimate-gas - Estimate gas for transaction
• GET /api/web3/balance - Get wallet balance

Users

• GET /api/users - Get users (admin only)
• GET /api/users/:id - Get user by ID
• PUT /api/users/:id - Update user

Project Structure

src/
├── config/
│   ├── database.js      # MongoDB connection
│   └── web3.js          # Web3 configuration
├── middleware/
│   ├── auth.js          # Authentication middleware
│   ├── errorHandler.js  # Error handling
│   └── validation.js    # Input validation
├── models/
│   ├── User.js          # User model
│   ├── Wallet.js        # Wallet model
│   └── Transaction.js   # Transaction model
├── routes/
│   ├── index.js         # Main router
│   ├── auth.js          # Auth routes
│   ├── users.js         # User routes
│   ├── wallets.js       # Wallet routes
│   ├── transactions.js  # Transaction routes
│   └── web3.js          # Web3 routes
├── controllers/         # Route controllers (to be implemented)
└── server.js           # Main server file

Development

Scripts

• npm run dev - Start development server with nodemon
• npm start - Start production server
• npm test - Run tests
• npm run lint - Run ESLint
• npm run lint:fix - Fix ESLint issues

Adding Controllers

The route files are set up but controllers need to be implemented. Create controller files in src/controllers/:

• authController.js
• userController.js
• walletController.js
• transactionController.js
• web3Controller.js

Security Features

• JWT token authentication
• Wallet signature verification
• Password hashing with bcrypt
• Rate limiting
• CORS protection
• Helmet security headers
• Input validation and sanitization

Contributing

1. Fork the repository
2. Create a feature branch
3. Commit your changes
4. Push to the branch
5. Create a Pull Request

License

MIT License