Mermaid is a text-based diagramming tool for people who would rather write diagrams than drag boxes around a canvas. It uses a Markdown-like syntax to describe flowcharts, sequence diagrams, class diagrams, state machines, timelines, Gantt charts, entity relationship diagrams, and more.
For a technical blog, Mermaid is a very good default. The diagrams live next to the article, they can be reviewed in Git, and they are easy to update when the system changes. Static image diagrams look nice until the first architecture change. Mermaid diagrams are not perfect, but they age much better.
This guide is a practical Mermaid quickstart and cheatsheet for developers, technical writers, and Hugo site owners. It is part of the Documentation Tools in 2026: Markdown, LaTeX, PDF & Printing Workflows hub.
What Is Mermaid?
Mermaid is a diagram-as-code syntax. You write a small text block, and Mermaid renders it as a diagram.
