Understanding the structure of large existing (and evolving) software systems is a major challenge for software engineers. In reverse engineering, we aim to compute, for a given software system, a decomposition of the system into its subsystems. CCVISU is a lightweight tool that takes as input a software graph model and computes a visual representation of the system's structure, i.e., it structures the system into separated groups of artifacts that are strongly related, and places them in a 2- or 3-dimensional space. Besides the decomposition into subsystems, it reveals the relatedness between the subsystems via interpretable distances. The tool reads a software graph from a simple text file in RSF format, e.g., call, inheritance, containment, or co-change graphs. The resulting system structure is currently either directly presented on the screen, or written to an output file in SVG, VRML, or plain text format. The tool is designed as a reusable software component, easy to use, a...