Student engagement in learning is crucial for academic achievement, motivation, and active participation. However, measuring and accounting for student engagement, both in face-to-face and online sessions, remains a challenge for educators. Existing methods, such as self-reports, interviews, and even real-time eye tracking tools, lack a multidimensional engagement approach (i.e., cognitive, affective, and behavioral). In response, this article presents the development of MoTE, a real-time tool for monitoring student engagement. Following a Design-Based Research methodology, we detail the phases of identification of indicators and visualizations to meet the needs of teachers and students, culminating with the proposal of the architecture, and the implementation of an initial prototype. It ends with the evaluation with 146 students in face-to-face and online contexts, providing valuable information on the indicators, dashboards, and functionalities to design an effective tool for monitoring student engagement. This work not only proposes an innovative approach to assessing engagement but also opens avenues for future research and practical applications in education.