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 programmatically generating complex diagrams, suitable for users with technical expertise, while OmniGraffle offers a more user-friendly interface and is tailored for macOS users who prefer a graphical approach to diagramming. Each has its strengths depending on the user's needs for automation versus ease of use.