An Internet-based goniometer has recently been developed which can be used for the remote quantification of joint range of motion (ROM). We evaluated the validity and intra- and inter-rater reliability of this goniometer for the measurement of upper limb ROM in 10 people who had had a stroke. The movements on which the device was evaluated were shoulder flexion, shoulder abduction, elbow flexion, wrist flexion, wrist extension, forearm supination and forearm pronation. Measurements performed using the Internet-based goniometer were compared with measurements made using the most widely accepted clinical joint ROM measurement tool, the universal goniometer. The Internet-based goniometer was found to be a valid tool for the measurement of upper limb ROM, with the disagreement between the two measurement tools ranging from 1.1-2.4 degrees. The internet-based goniometer was also shown to possess a high level of intra- and inter-rater reliability (all intraclass correlation coefficients>0.93). The results suggest that therapists can confidently use the Internet-based goniometer to measure the upper limb ROM in people who have had a stroke.