Developed a reading progress synchronization feature for the Kareadita/Kavita repository, enabling seamless cross-device progress updates between Koreader and Kavita. The work involved designing and implementing new API endpoints for authentication and progress updates, as well as creating robust data structures to manage synchronization state. Using C# for backend development and applying unit testing practices, the developer established an end-to-end sync flow that supports future enhancements and improves maintainability. This integration allows users to maintain consistent reading progress across platforms, addressing the need for continuity and laying a modular foundation for expanded functionality within the Kavita ecosystem.