Open Source Software (OSS) refers to software whose source code is publicly available, allowing its modification and distribution at no cost. However, due to these OSS projects' collaborative and community-based nature, they often lack resources to focus on quality aspects, such as efficiency and usability. This research aims to apply the adapted Interface Content Model usability technique in the open-source software Koodo Reader project. We participated as volunteers in this project, although we did not have the authorization of the leading developer. To validate the effectiveness of the adapted technique, tests were conducted with representative users, covering a variety of interactions with the Koodo Reader interface. The results of these tests were used for prototyping, which was evaluated and validated by the user community of the Koodo Reader project. In conclusion, the successful application of the Interface Content Modeling technique has proven to be a tool that helps improve the quality of projects. It makes it easier for the developer community to collaborate to improve the end-user experience and make the project more appealing to users. This case exemplifies how collaboration and teamwork in the OSS context can generate innovative and effective solutions.