Graphviz

Create graphs from text.

Graphviz is a tool for drawing graphs from given input. This allows them to be generated dynamically to illustrate hierarchies, networks, and other types of object and entity relationships.

Graphviz Filter Module

Drupal has the Graphviz Filter module, which lets you put graphs into your text. It's easy to configure and use, but limits you to static graphs. To really open up the features, we would need a views display, so hopefully that is available soon.

Other Graphing Tools

Mermaid JS

PlantUML