The wide variety of Android devices and operating system versions is also a big concern for any Android app development agency. To overcome this concern, JanBask Digital Design conducts intensive testing on a wide range of devices and OS versions. We are a mobile-first design team that can develop intuitive website designs for various screens and resolutions. We also write optimized code to guarantee fast performance regardless of the device configuration. The functional test, performance test, and compatibility test are conducted to highlight any abnormalities that occur due to changes made in the system. We test the app on mobile phones and computers running on different operating systems to prevent any exceptions for specific devices or operating systems.