Rumah Belajar is a free web-based application which can be used as a supplementary learning platform for students in Indonesia. Since its release, there has not been any research on its usability. To increase the satisfaction and comfort of the users, research about usability, evaluation is needed. This research is conducted to better understand the user needs and analyze the flaws of the application. Evaluation was done using a questionnaire and a system usability scale as the quantitative method along with usability testing and a contextual interview as the qualitative method. Through the user-centered design, research involved the users to make sure that the application is aligned with the users' expectations. The results of the research suggest that the usability of the Rumah Belajar application needs to be improved. The design is made in the form of a prototype that will solve the raised issues. The designed prototype was tested on the users through usability testing. After being tested, the new suggested design could solve the majority of the usability issues.