1st Team: 1. Primarily utilized PostgreSQL procedures to manage data flow and implement business logic. 2. Maintained the frontend (React.js) and the web server(Koa.js), and managed cron jobs using JavaScript. 2nd Team: 1. Employed TypeScript and dependency injection techniques to implement complex business logic. 2. Refactored JavaScript React.js code to TypeScript, utilizing Zustand for state management and @tanstack/react-query for improved frontend architecture, testability, and MVVM logic splitting, enhancing maintainability and scalability. 3. Managed GitLab CI pipelines and maintained Helm repositories. 4. Implemented Infrastructure as Code practices using Terraform. 5. Refactored TypeScript code using Domain-Driven Design (DDD), SOLID principles, and design patterns to improve testability, maintainability, and extensibility.