Graphviz

Graphviz is the classic, open-source tool for visualizing structural information as diagrams of graphs and networks. It uses the DOT language to define graphs, which are then automatically laid out by powerful algorithms. Graphviz is the engine behind many other diagramming tools and is widely used in academia and software engineering for visualizing complex data structures, call graphs, and dependency trees. While it lacks a graphical user interface, its ability to handle massive, complex graphs automatically makes it an essential tool for developers and researchers working with large datasets.