Clustering layouts of software systems combine two important aspects: they reveal groups of related artifacts of the software system, and they produce a visualization of the results that is easy to understand. Co-change visualization is a lightweight method for computing clustering layouts of software systems for which the change history is available. This paper describes CCVISU, a tool that implements cochange visualization. It extracts the co-change graph from a version repository, and computes a layout, which positions the artifacts of the software system in a two- or threedimensional space. Two artifacts are positioned closed together in the layout if they were often changed together. The tool is designed as a framework, easy to use, and easy to integrate into reengineering environments; several formats for data interchange are already implemented. The graph layout is currently provided in VRML and SVG format, in a standard text format, or directly drawn on the screen. 1 Concepts ...