Mermaid

What it does

Mermaid turns plain text into diagrams. You write a few lines in a simple syntax and it draws a flowchart, a sequence diagram, a Gantt chart, an entity-relationship diagram, a state diagram or one of many other types. Change the words and the picture redraws itself.

There are two things under the name. Mermaid.js is the open-source library, and the Mermaid Live editor lets you try it in the browser. Mermaid Chart, now at mermaid.ai, is the commercial product from the same team, with a visual editor, AI diagram generation, sharing and team features.

Why you would need it

Diagrams in documentation go stale. Someone draws the architecture in a design tool, exports a picture, pastes it in a doc and then the system changes. A year later nobody trusts the picture.

When the diagram is text, it lives in the repo, it is reviewed in a pull request and it changes with the thing it describes. I would look at Mermaid when you write documentation, runbooks or specs and want the diagrams to be as easy to update as a paragraph.

Where it fits

Mermaid sits inside your documentation workflow. Your code, your notes and your AI assistant feed it text. It feeds docs, wikis, issue trackers and slide decks with pictures. Mermaid lists plugins and apps for GitHub, Confluence, Jira, Google Docs, Word, PowerPoint, VS Code and JetBrains. It replaces a drawing tool for the diagrams that exist to explain something, not to impress.

What stands out

• Text-based diagrams that sit in version control and review like code.
• Many diagram types, including flowcharts, sequence, Gantt, ER, timeline, mind map, org chart and git graph.
• An official MCP server that lets an AI assistant validate and render diagrams, and manage them in your account.
• Real-time co-editing and a share link in Mermaid Chart.

My take

This is a documentation tool, and it is excellent at that. It also suits AI work well: a model writes Mermaid syntax far more reliably than it places boxes on a canvas, so an assistant can produce and update diagrams for you.

The trade-off is control. You describe intent and Mermaid decides the layout, so large diagrams can sprawl or cross lines in ways you cannot fully tame. A small syntax mistake can break the render with a terse error. For a polished one-off that must look designed, use a canvas tool such as Figma or Miro.

Verdict

Pick Mermaid if diagrams are a by-product of writing documentation and you want them versioned with your code. Skip it if the diagram is the deliverable and it needs pixel-level design.