The Express Card API is a simulation of a card-api integration. It features a modular architecture with the main entry point defined in 'index.js' and utilizes ECMAScript modules ('type': 'module')

It utilizes Express.js for web framework functionality, Nodemon for automatic server restarts, Body Parser for parsing HTTP request bodies, dotenv for environment variable management, MySQL2 for MySQL database connectivity, Node-fetch for making HTTP requests, and Sequelize as an ORM for interacting with the database.