Line9 MCP MCP server

A hosted MCP server that integrates Line9's Mermaid layout engine into AI assistants like Claude, ChatGPT, Cursor, and VS Code. It renders Mermaid source code with cleaner placement, orthogonal edges, and readable typography, displaying the result as a zoomable widget or providing an Open-in-Line9 link. It supports tools for rendering diagrams, listing published diagrams, and fetching specific diagram details.

Endpoint and access

No sign-in: your client connects and lists tools immediately, with no account or key.

No sign-inEndpoint checked 2026-10-05Operated by Line9

MCP endpoint (Streamable HTTP)

https://mcp.line9.ai/mcp

Vendor documentation

What you can do with it

Render Mermaid flowcharts with Line9's layout engine
List published diagrams in a Line9 workspace
Fetch and display a specific diagram by name or slug

Tools advertised by the last live check:

render_diagram
list_diagrams
get_diagram

Connect from your client

Each snippet registers the same endpoint; pick the client you use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Claude Code

Run this once in a terminal. It registers a Streamable HTTP server. Use --scope project to write .mcp.json for the repo.

Claude Code configuration

claude mcp add --transport http line9-mcp https://mcp.line9.ai/mcp

Codex

Run this once. Codex stores MCP servers in ~/.codex/config.toml (or .codex/config.toml in a trusted project).

Codex configuration

codex mcp add line9-mcp --url https://mcp.line9.ai/mcp

Cursor

Merge this server into .cursor/mcp.json in your project, then enable line9-mcp in your MCP settings.

Cursor configuration

{
  "mcpServers": {
    "line9-mcp": {
      "url": "https://mcp.line9.ai/mcp"
    }
  }
}

Cline

Merge this into cline_mcp_settings.json (Cline → MCP Servers → Configure). The type must be streamableHttp for a remote HTTP server.

Cline configuration

{
  "mcpServers": {
    "line9-mcp": {
      "type": "streamableHttp",
      "url": "https://mcp.line9.ai/mcp",
      "disabled": false
    }
  }
}

VS Code

Merge this server into .vscode/mcp.json. Use MCP: List Servers to start line9-mcp and inspect its tools.

VS Code configuration

{
  "servers": {
    "line9-mcp": {
      "type": "http",
      "url": "https://mcp.line9.ai/mcp"
    }
  }
}

Gemini CLI

Run this once. It writes .gemini/settings.json in the current project; pass --scope user for ~/.gemini/settings.json.

Gemini CLI configuration

gemini mcp add --transport http line9-mcp https://mcp.line9.ai/mcp

Claude Desktop

Merge this into claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\), then restart Claude Desktop.

Claude Desktop configuration

{
  "mcpServers": {
    "line9-mcp": {
      "url": "https://mcp.line9.ai/mcp"
    }
  }
}

Windsurf

Merge this into ~/.codeium/windsurf/mcp_config.json, then refresh MCP in Cascade. Windsurf remote servers use serverUrl, not url.

Windsurf configuration

{
  "mcpServers": {
    "line9-mcp": {
      "serverUrl": "https://mcp.line9.ai/mcp"
    }
  }
}

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