mermaid-live-mcp

MCP server for generating Mermaid diagrams with live browser preview. Renders diagrams in real-time and supports SVG/PNG export.

<a href="https://npmjs.com/package/mermaid-live-mcp"><img src="https://img.shields.io/npm/v/mermaid-live-mcp" alt="npm version"></a>

<p align="center"> <img src="demo.gif" alt="mermaid-live-mcp demo" width="800" /> </p>

Install

Claude Desktop

Add to your Claude Desktop config (~/Library/Application Support/Claude/claude_desktop_config.json on macOS):

{
  "mcpServers": {
    "mermaid": {
      "command": "npx",
      "args": ["-y", "mermaid-live-mcp"]
    }
  }
}

Cursor

Add to .cursor/mcp.json in your project root:

{
  "mcpServers": {
    "mermaid": {
      "command": "npx",
      "args": ["-y", "mermaid-live-mcp"]
    }
  }
}

Claude Code

claude mcp add mermaid -- npx -y mermaid-live-mcp

Windsurf

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "mermaid": {
      "command": "npx",
      "args": ["-y", "mermaid-live-mcp"]
    }
  }
}

Tools

Tool	Description
generate_mermaid	Generate a diagram from Mermaid syntax and open a live preview in the browser
update_diagram	Replace a diagram's Mermaid syntax and re-render the live preview
list_diagrams	List all diagrams generated in the current session
export_diagram	Write a diagram's SVG to disk

How it works

When you ask your AI assistant to create a diagram, mermaid-live-mcp will:

1. Parse the Mermaid syntax
2. Open a browser tab with a live preview
3. Render the diagram as SVG in real-time via WebSocket
4. Provide download buttons for SVG and PNG export

Updates to a diagram are pushed instantly to the browser — no page refresh needed.

Supported diagram types

All Mermaid diagram types are supported, including flowcharts, sequence diagrams, class diagrams, state diagrams, ER diagrams, Gantt charts, pie charts, git graphs, mindmaps, timelines, and more.

Development

pnpm install
pnpm build

Project structure

Package	Description
packages/mcp-server	MCP server (published as mermaid-live-mcp)
packages/preview	Live browser preview via WebSocket
packages/core	Diagram parsing, layout, and SVG rendering
packages/cli	Command-line interface

License

MIT