Open Source Software (OSS) is software whose source code is accessible to the public, allowing its modification and distribution at no cost. This feature encourages the active collaboration of the community of developers, who come together to learn and contribute to the project. The objective of this research work has been to validate the incorporation of the adapted State Transition Diagrams technique in the Open Source Software project "Sports Tactics Board" to improve its usability. The research results reveal that implementing this technique facilitated the understanding of the requirements and functionalities of the software, as well as the identification and efficient resolution of errors. In addition, using the State Transition Diagrams technique increased user satisfaction and adoption of the software. Despite the challenges and difficulties encountered in applying this technique, such as the need for closer collaboration between developers and usability experts, the findings indicate that implementing techniques during the OSS development process can significantly improve its usability.