The article addresses the issue of minimalism in User Interface (UI) design of online courses. The paper debates the latest researches related to UI design, the quality of which influences the success of educational platforms. The analysis, which we carried out, allowed us to focus on such minimalism criteria of online courses that provide students’ satisfaction with online education. The research considers the design tools that are used to achieve minimalistic UI of mathematical and methodical courses on the platform “Higher School Mathematics Teacher”. The article discusses the creation of a minimalistic UI model and web tools search to develop it. During the survey, the answers, which were given by 203 volunteers, who became the first users of platform courses, allowed determining the directions of interface improvement on the platform “Higher School Mathematics Teacher. The received average estimate confirmed the interface minimalism of the online courses published on the platform “Higher School Mathematics Teacher”.