Mental health problems are a major public health concern worldwide. Approximately 50% of the population will experience mental problems during their life. Traditional treatment is based on psychopharmacotherapy or psychotherapy, with face-to-face interaction between the patient and the therapist. New technologies such as Internet-delivered treatments are seen as an opportunity to offer more scalable and cost-efficient treatments in the field of mental health. Despite the growing interest and new evidence supporting the effect of Internet-delivered treatments is it remarkably little research on how the technology and the usability of Internet-delivered treatment programs affects the treatment. In this paper, we propose a set of evaluation criteria for evaluating the usability and the responsive design of Internet-delivered treatment systems. By our knowledge we are the first to include usability and universal design principles in the evaluation of Internet-delivered treatment systems. Our findings indicate that despite the good treatment results and proven clinical effects, the systems in general have several issues regarding usability, universal design and outdated technology. Based on our findings we propose that there should be established guidelines for testing the usability and technology of Internet-delivered treatment systems.