Bubble size distribution (BSD) is a factor that is well known for influencing the performance of many industrial processes, such as froth flotation. The most commonly used method for measuring bubble size consists of processing photographs of the bubbles. However, the source code of the algorithms for performing the image processing has been seldom published. This article addresses the above by presenting a comprehensive open-source software for processing images of bubbles, allowing researchers to quantify BSD. This software - Bubble Analyser - includes a standard image processing algorithm that was tested against manually segmented images, showing errors under 5% in the calculation of the Sauter mean diameter, the most common descriptor of BSD. Additionally, Bubble Analyser has been designed to easily incorporate new segmentation algorithms developed by other researchers, in order to expand the software capabilities, allow for algorithm comparisons, and foster collaboration in research.