Background: Outcome research has highlighted the efficacy of internet-based cognitive behavioural therapy (iCBT). Some process research has examined users experiences of iCBT. Understanding the user experience provides valuable feedback to developers of internet-delivered interventions. Aim: The present study aimed to evaluate user's experiences and engagement with the design features of an internet-delivered treatment programme for anxiety. Methods: Semi-structured interviews were conducted with 7 participant users of the "Space from Anxiety" programme. A thematic analysis framework was employed to analyse the data collected. Results: Identified themes related to participants engagement and adherence with the programme material, participant's experience of personal development through interaction with the programme content and participants experience of the social features employed in the programme. Another theme investigated the various attributes or conditions necessary for internet-delivered therapy to be helpful to an individual. Conclusion: Considering the experiences of users of online interventions provides insight into what works for whom both in terms of technological features and the various skills and strategies that may compose the treatment intervention. Knowing more about what design features and strategies/components of the intervention are attractive and keep users involved can only enhance the delivery of effective internet-delivered interventions for anxiety disorders.