During our internship, my team was assigned to enhance an existing internal system called One App, which functions as a master platform for managing various company services. Our task was to develop a new feature that controls user accessibility across different services. Specifically, we built the Roles and Access and Service Accessibility modules. I was primarily responsible for the Roles and Access feature, where users' access to specific functionalities can be enabled or disabled based on their assigned roles. In collaboration with my partner, we designed the UI mockups in Figma, developed the business logic, and implemented the database structure. We used modern technologies such as T3 Stack, Next.js, Tailwind CSS, Prisma, and shadCN UI to bring the feature to life. The feature successfully improved access control within the system and contributed to the platform's scalability.