Graphviz (Graph Visualization Software) is a package of open-source tools initiated by AT&T Labs Research for drawing graphs specified in DOT language scripts. Developed by AT&T Research Labs and Contributors
License: Open Source
Graphviz is an open-source tool focused on graph visualization and layout generation with a steeper learning curve, while Tom Sawyer Software offers a more user-friendly interface with advanced features for complex data visualization, albeit at a cost.