Background: Inflammatory arthritis (IA) encompasses autoimmune rheumatic diseases, such as rheumatoid arthritis, psoriatic arthritis, and axial spondyloarthritis. Fatigue is highly prevalent in people with IA with 41-57% suffering from severe fatigue. Patients describe fatigue as overwhelming, unpredictable, challenging to manage, and affecting all areas of everyday life, including the ability to work. Studies have shown that interventions with physical activity or a cognitive behavioral approach can significantly reduce fatigue severity and/or impact in people with IA compared to usual care. To date, no studies have investigated the combined effect of CBA and PA on fatigue severity and impact in patients with IA. Therefore, the goal of this study is to test the feasibility of a newly developed fatigue intervention that combines a cognitive behavioral approach and physical activity (COMFI) in patients with inflammatory arthritis, who experience fatigue as a challenge in their everyday lives in Denmark and Sweden. The intervention will be tested in 4 groups (2 in Denmark and 2 in Sweden), and the participants will participate in 7 group sessions and 2 focusgroups interview in the evaluation. The primary outcome for the participants is fatigue, measured through patient-reported outcomes at baseline, 3, 6, and 12 months after baseline. This study will show if the intervention is feasible in practice and meaningful for the participants.