The performance of CBCT software plays an important role in analyzing a CBCT image. Several types of software are available, which can be accessed as open-source and commercial software. There are several studies about the performance of open-source CBCT software, however, there have not been any publications about the comparison of the performance of opensource software to commercial software in measuring TMJ joint space yet. The aim of this study is to examine the reliability of TMJ joint space measurement on CBCT images using open-source and commercial software through intra-interobserver measurement. TMJ joint space measurement from secondary CBCT data from the dental hospital Faculty of Dentistry Universitas Indonesia was performed using three different software i.e. open-source software Horos, ITK-Snap, and commercial software CS 3D dental imaging. Technical Error of Measurement (TEM) obtained a value of d < 1, showing good reliability of intra and interobserver measurements of those three different software in measuring TMJ joint space. This study shows that the result obtained from intra- and interobserver in measuring the TMJ joint space from all software was reliable. © (2023), (University of Dicle). All Rights Reserved.