Development of a file synchronization system requires careful handling of several concerns such as transactions, fault-tolerance, and security. Very often these concerns are hard to modularize into first class elements using tradi-tional software development paradigms. Such cross-cutting concerns decrease the cohesion and increase coupling of the components of the file synchronization system. Aspect-Oriented Software Development (AOSD) provides explicit abstractions to address these cross-cutting concerns. In this paper, we go through the development process of a secure peer-to-peer file synchronization application, FSync, and AOSD techniques to enhance separation of concerns.