Background and objective: Currently, the lack of tools for physiotherapists, and the quality of these tools when physiotherapists assess patients does not allow a good diagnosis. Accurate joint range evaluation is an essential task in the daily work of physiotherapists in order to correctly assess treatment progress. In this study, we examined the reliability and safety of an Android system application called G-Pro to evaluate its characteristics and observe its usefulness as a goniometer to measure joint angles in a clinic. Material and methods: The standard goniometer and G-pro smartphone with the application were used to passively and bilaterally measure shoulder flexion and rotation and elbow flexion in 30 participants able to tolerate standing. Results: The G-pro smartphone application showed good to excellent reliability (r = 0.998 to 0.896, P < .01), while the universal goniometer showed acceptable to questionable reliability (r = 0.757 to 0.609) in active shoulder flexion-extension movement. Conclusions: The results obtained in this study show that these devices represent an additional resource to assess joint mobility ranges. Due to technological progress, we can improve, innovate, and demonstrate the results of joint assessments to ensure their accuracy. This, in turn, ensures that the treatment provided is appropriate and specific to each patient. This tool is low cost and is accessible for health care professionals; moreover, it is easy to use since it has an incliniometer that is reliable both visually and evaluatively.