In the Application Design and Development course, I developed a full-stack application using Ruby on Rails. The application maintains internal cafe operations with a strong focus on MVC structure. Based on the level of permissions (admin, manager, employee, and regular visitor) users can view and control different things like store, payroll, shift, job management, etc. I also produced APIs to efficiently retrieve critical JSON data using serializers and enhanced security for different access levels through extensive testing to reach 100% coverage testing.