Mermaid Chart MCP Server

Official Mermaid Chart MCP server that validates, renders, titles, and manages Mermaid diagrams through hosted HTTP and SSE endpoints.

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Overview

The Mermaid Chart MCP server is the official, provider-hosted MCP integration from the team behind Mermaid Chart (mermaid.ai). It lets AI assistants generate, validate, and render Mermaid diagrams (flowcharts, sequence diagrams, ERDs, Gantt charts, state machines, and more) without any local installation. The server returns PNG/SVG output along with an interactive playground link for editing, so agents can iterate on diagrams in conversation and hand them back as embeddable assets.

The server is split into two tiers. The core tools (validation, rendering, title and summary generation, tool listing) require no authentication and work against the public endpoint. A second set of tools provides full integration with a Mermaid Chart account, letting an agent list projects, list diagrams in a project, and create, fetch, and update diagrams stored in the user's workspace. These authenticated tools require an API token from Mermaid Chart account settings.

It is delivered as a remote MCP server at https://mcp.mermaid.ai/mcp (Streamable HTTP) with a legacy SSE endpoint at https://mcp.mermaid.ai/sse. Because it is hosted by Mermaid Chart, there is nothing to install locally, just a URL and an optional bearer token in the client configuration.

Tools

Tool	Description
`validate_and_render_mermaid_diagram`	Validates Mermaid syntax and renders the diagram as PNG/SVG with a playground link for editing.
`get_diagram_title`	Generates a descriptive title for a given Mermaid diagram.
`get_diagram_summary`	Produces a concise summary describing what the diagram represents.
`list_tools`	Lists all tools exposed by the Mermaid Chart MCP server.
`list_mermaid_chart_projects`	Lists projects in the authenticated user's Mermaid Chart workspace. Requires auth.
`list_mermaid_chart_diagrams`	Lists diagrams inside a specific Mermaid Chart project. Requires auth.
`create_mermaid_chart_diagram`	Creates a new diagram in a Mermaid Chart project. Requires auth.
`get_mermaid_chart_diagram`	Retrieves a specific diagram from the user's Mermaid Chart account. Requires auth.
`update_mermaid_chart_diagram`	Updates the source of an existing Mermaid Chart diagram. Requires auth.

Setup Guide

Setup

The Mermaid Chart MCP server is hosted by Mermaid Chart. There is no package to install. Point your MCP client at the remote URL.

Prerequisites

An MCP-compatible client (Claude Desktop, Cursor, VS Code, Antigravity, etc.)
Optional: a Mermaid Chart account and API token (required only for the project/diagram management tools). Generate one in account settings on mermaid.ai.

Claude Desktop / VS Code (unauthenticated, core tools only)

{
  "servers": {
    "mermaid-mcp": {
      "url": "https://mcp.mermaid.ai/mcp",
      "type": "http"
    }
  }
}

Claude Desktop / VS Code (authenticated)

{
  "servers": {
    "mermaid-mcp": {
      "url": "https://mcp.mermaid.ai/mcp",
      "type": "http",
      "headers": {
        "Authorization": "YOUR_MERMAID_CHART_TOKEN_HERE"
      }
    }
  }
}

Cursor

{
  "mcpServers": {
    "mermaid-mcp": {
      "transport": "http",
      "url": "https://mcp.mermaid.ai/mcp"
    }
  }
}

Antigravity (uses mcp-remote proxy)

{
  "mcpServers": {
    "mermaid": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "--header",
        "Authorization:YOUR_TOKEN",
        "https://mcp.mermaid.ai/mcp"
      ]
    }
  }
}

Legacy SSE endpoint

If your client only supports SSE, use https://mcp.mermaid.ai/sse with "type": "sse". The HTTP endpoint is preferred.

Use Cases

Have an AI agent draft architecture diagrams or flowcharts from natural language and instantly validate and render them to PNG/SVG.
Generate sequence diagrams or ERDs from code or schema descriptions during a design review, then save them to a Mermaid Chart project.
Auto-document features by asking the agent to produce a Mermaid flowchart and update the canonical diagram stored in the team's Mermaid Chart workspace.
Title and summarize existing diagrams when migrating or organizing a large library inside Mermaid Chart.
Embed agent-generated diagrams in PR descriptions, Notion pages, or Confluence docs using the playground links returned by the render tool.

Example Prompts

"Draft a Mermaid sequence diagram for our OAuth login flow and render it as a PNG."
"Validate this Mermaid flowchart and fix any syntax errors, then give me the playground link."
"List all projects in my Mermaid Chart account and show the diagrams in the Architecture project."
"Create a new Mermaid ERD for the billing schema and save it to my Mermaid Chart 'Backend' project."
"Update diagram abc123 in Mermaid Chart so the Payments service points to the new Stripe webhook handler."

Pros

Official, provider-hosted server. No installation, runtime, or local rendering pipeline needed.
Core validation, rendering, and summarization tools work without authentication, so it is easy to try.
Full read/write access to projects and diagrams when authenticated, so agents can persist work instead of producing one-off images.
Returns interactive playground links alongside PNG/SVG output, useful for handoff and embedding.

Limitations

The full project and diagram management tools require a Mermaid Chart account and API token.
The server is closed-source and hosted only by Mermaid Chart, so there is no option to self-host.
The legacy SSE endpoint is deprecated, and some MCP clients still require the mcp-remote proxy to use the Streamable HTTP endpoint.

Alternatives

peng-shawn/mermaid-mcp-server: Community, self-hosted MCP server that renders Mermaid diagrams to PNG/SVG.
hustcc/mcp-mermaid: Community MCP server that generates Mermaid diagrams with multiple export formats (svg, png, base64, file).
abekdwight/mermaid-mcp-server: Community server focused on Mermaid syntax checking and SVG rendering.