Our website provides a free download of Graphviz 2.4 for Mac. The software relates to Design & Photo Tools. The actual developer of this free Mac application is Pixelglow Software.
From the developer:
Graphviz is Open Source graph-visualization software. Graph visualization is a way of representing structural information as diagrams of abstract graphs and networks. It has important applications in networking, bioinformatics, software engineering, database and web design, machine learning, and in visual interfaces for other technical domains.
You may want to check out more Mac applications, such as XDot, Synalyze It! Pro or Trout Mind Mapping, which might be similar to Graphviz.