Mermaid | Diagramming and charting tool
Diagram as Code
Open-source tool that uses simple textual descriptions to draw beautiful UML diagrams.
It's Time to Drop Drag-and-Drop Architecture Diagramming
GitHub - threatcl/threatcl: Documenting your Threat Models with HCL
Uses HCL to produce PNGs and diagrams, can import assets from Terraform configs
Argues that threats are accidental, based on tradeoffs, or inherent and how to deal with these varies.