In this thesis the design and analysis of a passive exoskeleton to assist the elderly and workers for overhead tasks are presented. The scope of the exoskeleton is to compensate for the gravitational forces. The exoskeleton consists of a spherical shoulder mechanism and a passive variable stiffness mechanism. Both mechanisms are described and further ideas are presented. Numerical, analytical and experimental analyses of the variable stiffness mechanism are carried out and compared. Furthermore, topology optimisation is performed to reduce weight. The exoskeleton focuses on assistance in the sagittal plane, but due to the properties of the modules, also motion in different planes is supported. The final design compensates for $50\%$ of the gravitational torque of the arm with the elbow stretched.