Abstract: The present disclosure is related in general to performance assessment and a method and a system for determining performance of an application installed on mobile stations. An application performance detection system configures each of the mobile stations upon receiving a performance assessment request to ensure deactivation of hardware and software modules that cause additional network traffic and resource utilization. Further, the application performance detection system receives application data from the mobile stations thus configured and determine Key Performance. Indices (KPIs) based on the application data. Rating of the application is determined based on the KPIs that can efficiently detect low rated application design that requires re-engineering. Finally, performance of the application is verified that helps in achieving significant reduction in operational data costs, improved device battery life, improved user experience and efficient network resource usage.