A Mobile Web Testing developer is responsible for testing mobile web applications to ensure optimal performance across various mobile devices and platforms. They create and execute test cases, identify and report bugs, and verify bug fixes. They use tools for automation testing and simulate different network environments. They also ensure the web application's user interface and functionalities work well on different screen sizes and orientations. Additionally, they check the app's compatibility with different browsers and operating systems. It's their duty to ensure a seamless and efficient user experience for all mobile web users.