Mixed reality (MR) technology brings together the real and the digital world. In MR, users have access to both physical and virtual items and can manipulate them. Such technology can support users from different perspectives depending on the task, context, and user characteristics. During the last years, researchers have used MR and eye tracking technology in combination in order to achieve different goals such as eye-based interactions, guide attention, ease collaboration, etc. In this research project, we focus on designing and developing MR applications that work based on eye tracking technology integrated into HoloLens 2.