• A diagnosis of autism, based on the diagnostic criteria of the 4th or 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM) or the 10th edition of the International Classification of Diseases (ICD-10). Informed by the parent/caregiver and subsequently confirmed by review of the medical record or the neurodevelopmental assessment report. A diagnosis of autism will be considered present if it was established with validated instruments, such as the Autism Diagnostic Interview-Revised (ADI-R), the Autism Diagnostic Observation Schedule (ADOS) edition 1 or 2 or the Diagnostic Interview for Social and Communication Disorders (DISCO; autism or ASD cut-offs).

• A DSM-5 or ICD-10 diagnosis of OCD. Confirmed by the assessor at the inclusion assessment, based on a structured diagnostic interview.

• A total score of ≥16 on the CY-BOCS. Confirmed by the assessor at the inclusion assessment.

• Age between 7 and 17 years. Confirmed by the caregiver and subsequently by the medical record system.

• Ability to read and write Swedish. Confirmed by the caregiver at the telephone screening or/and the inclusion assessment.

• Regular access to a computer or a smartphone/tablet connected to the internet, and a mobile phone to receive text messages. Confirmed by the caregiver at the telephone screening or/and inclusion assessment.

• A parent/caregiver able to participate in the treatment alongside their child. Confirmed by the caregiver at the telephone screening or/and the inclusion assessment.