The purpose of this study was to develop a list of usability guidelines, i.e. a usability checklist, which can assist in evaluating the usability of Massive Open Online Courses (MOOCs) user interfaces. Interviews were conducted to help understand their context of use and to find design focus points for the evaluation of MOOCs interface. These design focus points were then inspected for usability issues with Jakob Nielsen’s usability inspection method - heuristic evaluation - using author’s own set of 10 usability heuristics. The study reveals two main findings. Firstly, the context of use of MOOCs differs from a regular university course in the manner of how users perceive and approach them. And secondly, the usability checklist has to be adaptable and up-to-date in order to support the constant change of context of use of MOOCs. The combination of both findings is what makes this study not just another checklist, but a valid contribution to the understanding of MOOCs and the research field in HCI.