As mobile devices become prevalent, there is always a need for apps. How hard is it to develop an app, especially a cross-platform app? The paper shares an experience in a project that involved the development of a student services web app that can be run on cross-platform mobile devices. The paper first describes the background of the project, the clients, and the proposed solution. Then, it focuses on the step-by-step development processes and provides the illustration of written codes and techniques used. The goal is for readers to gain an understanding on how to develop a mobile-friendly web app. The paper concludes with teaching implications and offers thoughts for further development.