Zen API

A comprehensive fintech API built with TypeScript, Express, and MongoDB that provides secure financial services including multi-currency wallets, currency exchange, and virtual card management.

Features

• Authentication & Authorization - JWT-based secure user authentication
• Multi-Currency Wallets - Support for USD, NGN, GHS, and KES currencies
• Currency Exchange - Real-time FX quotes with Redis caching
• Virtual Cards - VISA virtual card creation and management
• Payment Processing - Paystack integration for deposits and payments
• Webhook Handling - Secure webhook processing for external services

Tech Stack

• Runtime: Node.js with TypeScript
• Framework: Express.js with routing-controllers
• Database: MongoDB with Mongoose ODM
• Caching: Redis for FX quotes and session management
• Authentication: JWT tokens
• Validation: class-validator with DTOs
• Testing: Jest with comprehensive unit tests
• Dependency Injection: TypeDI container
• Payment Gateway: Paystack
• Card Provider: Maplerad

Architecture

The API follows a clean, modular architecture with:

• Domain-Driven Design - Organized by business domains (auth, wallets, cards, etc.)
• Dependency Injection - Loose coupling with TypeDI
• Service Layer Pattern - Business logic separated from controllers
• DTO Validation - Type-safe request/response handling
• Centralized Error Handling - Custom error classes with proper HTTP status codes

Getting Started

Prerequisites

• Node.js (v14 or higher)
• MongoDB database
• Redis server
• Maplerad account for card services
• Paystack account for payments

Installation

1. Clone the repository:

git clone https://github.com/jason-ezenwa/zen-api.git
cd zen-api

2. Install dependencies:

npm install

3. Set up environment variables:

cp .env.example .env

4. Run database migrations:

npm run migrate-db

5. Start the development server:

npm run dev

The API will be available at http://localhost:3000

Scripts

• npm run dev - Start development server with hot reload
• npm run build - Build TypeScript to JavaScript
• npm start - Start production server
• npm test - Run test suite
• npm run migrate-db - Run database migrations
• npm run create-db-migration - Create new migration

Testing

The project includes comprehensive unit tests with Jest:

npm test

Tests cover:

• Authentication service logic
• Wallet operations and funding
• Currency exchange functionality
• Virtual card management
• Error handling scenarios

Deployment

The API is deployed and accessible at: https://zen-api-68zd.onrender.com

Production Deployment

1. Build the project:

npm run build

2. Set production environment variables

3. Run migrations and start:

npm start

Security Features

• Input Validation - All endpoints use DTOs with class-validator
• Authentication - JWT-based with proper token verification
• Authorization - Route-level access control
• IP Whitelisting - Webhook endpoints verify source IP addresses
• Error Handling - Secure error responses without sensitive data exposure
• CORS - Configured for cross-origin requests

Supported Currencies

• USD - US Dollar
• NGN - Nigerian Naira
• GHS - Ghanaian Cedi
• KES - Kenyan Shilling

Virtual Card Brands

• VISA

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

This project is licensed under the GNU General Public License v3.0 - see the LICENSE.md file for details.

Contact

For questions or support, contact me via email @chukwuemelie.ezenwa@gmail.com