Online mental health programs can be effective in reducing symptoms of depression, anxiety disorders, substance use and suicidal ideation. However, most existing e-mental health programs focus on a single domain of mental health, neglecting comorbidity. Furthermore, few programs are tailored to the symptom patterns of the individual user. FitMindKit was designed to overcome the gaps of existing e-mental health programs, providing tailored, transdiagnostic therapeutic content to address a range of comorbid mental health symptoms. The program has recently been trialled and will be further modified in response to the findings.