Nowadays, high-quality user experience (UX) has become a key competitive factor for product development. User experience methods and techniques investigate how people feel about a system. However, we must take into account that traditional evaluation methods, whether interviews or surveys are based on self-reported data, which are often exposed to social desire. Therefore, by obtaining additional information from the user's interaction with the system being evaluated, besides interviews or surveys, we build a more robust user experience. In this research, we present the outcomes of a Systematic Literature Review (SLR) aimed at uncovering case studies, difficulties, issues, and opportunities related to the use of heatmaps in usability testing. The SLR was carried out using the protocol proposed by Kitchenham and Charters. The research was carried out on August 23, 2022, and a total of 371 articles were retrieved, from which 22 were selected. The results show that a formal process reported in the literature has not been identified that indicates the tasks that an evaluation team should carry out to complement the results of the heatmap application with user tests for a better analysis of usability problems and design errors. On the other hand, it can be seen that the tools necessary to carry out this analysis only obtain information from the user but do not obtain metrics from it or vice versa. According to the results obtained, we can conclude that heatmaps are useful for specialists who perform usability tests with users because the user's interaction with the system to be evaluated can be graphically visualized.