The subject of this paper is the creation of a mobile application for tracking costs, on the Android platform, using the Java programming language. Although there is a large number of similar applications on the market, they are often complicated to use due to the number of the features they offer. For this reason, the mobile application from this paper enables the entry of new transactions with just a few taps on the smartphone screen, and this was achieved through a simplified interface, reducing the number of options within the applications and using automation. At the beginning of the work there is an introduction to the Android operating system, SQLite database and Java programming language, and in the practical work the process of creating the application, its functionalities and performance details are described. The Android operating system was chosen due to its widespread use and market share. SQLite was chosen as the database because of the small resources required for its operation while achieving the full functionality of a relational database, while Java was chosen as the programming language for application development because of the ability to run on all types of mobile platforms and the ease of learning and use.