Mermaid Studio

Let AI create diagrams for you. Mermaid Studio is a diagram editor with a built-in MCP server — connect Claude, Cursor, or any MCP-compatible AI and say _"draw me a flowchart"_.


Why MCP?

Traditional diagram tools require manual drawing. With MCP, AI tools can create, edit, and manage diagrams programmatically through a standard protocol:

You: "Draw a sequence diagram for OAuth2 login flow"
AI:  creates the diagram → you see it instantly in your browser
You: "Add error handling paths"
AI:  updates the same diagram → preview refreshes in real-time

The AI gets 7 tools (create_diagram, update_diagram, get_diagram, list_diagrams, delete_diagram, export_diagram, get_templates) and can work with all 9 Mermaid diagram types.

Connect in 30 Seconds

After registration, click the MCP button in the top bar to get a ready-to-paste config:

Claude Desktop / Claude Code / Cursor: ``json { "mcpServers": { "mermaid-studio": { "url": "https://your-worker.workers.dev/mcp", "headers": { "Authorization": "Bearer your-token" } } } } ``

Each user gets their own workspace — diagrams are isolated, and the AI only sees yours.

Note for China / restricted network users: Cloudflare Workers (*.workers.dev) may not be directly accessible in certain regions. You will need a VPN/proxy tool with enhanced/global mode that intercepts all system traffic (e.g., Surge Enhanced Mode, Clash TUN mode), as most proxy tools only cover browser traffic and not CLI/Node.js processes.

Features

• MCP server — AI creates/edits diagrams via standard protocol, real-time sync to browser
• Live editor — CodeMirror + Mermaid.js preview, 9 diagram types
• Multi-user — registration, workspace isolation, token-based auth
• Real-time — WebSocket updates via Durable Objects
• Version history — 50 versions per diagram, one-click restore
• Export — SVG / PNG / batch export
• Dark mode
• Cloudflare Turnstile — optional anti-bot protection for registration

Deploy Your Own

1. Create D1 Database

npm install
npx wrangler login
npx wrangler d1 create mermaid-studio-db

Copy the returned database_id into wrangler.toml.

2. Run Migrations

npm run db:migrate

3. Deploy

npm run deploy

4. (Optional) Add Turnstile Protection

Create a Turnstile widget at Cloudflare Dashboard, then:

# Add site key to wrangler.toml [vars]
# TURNSTILE_SITE_KEY = "your-site-key"

# Set secret key
npx wrangler secret put TURNSTILE_SECRET_KEY

Without Turnstile, registration works without human verification.

Local Development

npm run db:migrate:local
npm run dev

MCP Tools

| Tool | Description | Parameters | |------|-------------|------------| | create_diagram | Create a new diagram | name, type?, code | | update_diagram | Update existing diagram | diagram_id, code, name? | | get_diagram | Get diagram details | diagram_id | | list_diagrams | List all diagrams | - | | delete_diagram | Delete a diagram | diagram_id | | export_diagram | Export with URL | diagram_id, format? | | get_templates | Get starter templates | - |

Supported diagram types: flowchart, sequence, class, state, ER, gantt, pie, swimlane, mindmap

Architecture

workers/src/
  index.js          Hono router, API routes, auth middleware
  diagrams.js       D1 CRUD for diagrams
  users.js          User auth (PBKDF2 hashing)
  mcp.js            MCP protocol handler (JSON-RPC)
  websocket.js      Durable Object for real-time sync
  templates.js      9 diagram templates
public/             SPA frontend (CodeMirror + Mermaid.js)
migrations/         D1 database schema

Stack: Cloudflare Workers + D1 + Durable Objects + Hono

License

MIT