Mermaid

Mermaid lets you write diagrams as text and renders them as visuals. Instead of dragging shapes around in a GUI tool like draw.io, you describe your diagram in a lightweight syntax, and Mermaid generates the image. That means diagrams live alongside your code, version-control cleanly, and update without hunting through a visual editor.

It's built for developers, technical writers, and teams who want diagrams embedded in documentation, READMEs, wikis, or markdown-based doc platforms. Many tools that handle technical documentation support Mermaid natively, so diagrams render inline without any extra setup.

The diagram types it supports cover a wide range:

• Flowcharts for process and decision logic
• Sequence diagrams for showing interactions between systems or actors
• Gantt charts for project timelines
• Class and entity-relationship diagrams for data modeling
• State diagrams, pie charts, quadrant charts, and more

The syntax is intentionally minimal. A few lines of text produce a clean, readable diagram. Because everything is plain text, diagrams fit naturally into pull requests, code reviews, and documentation pipelines.

Beyond the core library, Mermaid also offers a live editor and a collaborative platform at mermaid.ai, where teams can build and share diagrams together. The live editor is useful for prototyping a diagram before dropping the syntax into a doc or codebase.

Mermaid integrates with a broad set of tools including GitHub (which renders Mermaid natively in markdown), Notion, Confluence, and various static site generators. For teams building data dashboards or internal tools, embedding Mermaid diagrams into existing workflows is straightforward.

The project is open source and actively maintained by a sizable core team.