The goal of this paper is to show, in theory, and practice, the development of an information system that uses a service to communicate with multiple clients. The system is intended for tennis coaches and players with the purpose of tracking data of trainings that coaches add for their players. This paper begins with planning and setting the system requirements and continues with system modeling and database creation with all the necessary tables and stored procedures. Later, the paper describes the development of REST service architecture through multiple layers with emphasis on production technology, scalability, asynchronous communication with the database, security, and authorization. Further on, the paper describes the production of client applications that use the service. The first and the main client is a single-page web application built with Angular technology. During the production, the paper describes the Angular architecture, its components, service classes and the usage of Angular Material library for designing the user interface of the application. The second client is a native Android application that coaches can use to view the basic data of their players and trainings. The paper shows how specific possibilities of the Android platform can contribute to the entire system such as activities, fragments, local storage, and internationalization. Finally, the paper describes the deployment of the system and its components.