Content
# MCP Excalidraw Server: Advanced Live Visual Diagramming with AI Integration
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A comprehensive **TypeScript-based** system that combines **Excalidraw's powerful drawing capabilities** with **Model Context Protocol (MCP)** integration, enabling AI agents to create and manipulate diagrams in real-time on a live canvas.
## 🚦 Current Status & Version Information
> **📋 Choose Your Installation Method**
| Component | Local | Docker | Status |
|-----------|-------|--------|--------|
| **Canvas Server** | ✅ Fully Working | ✅ Fully Working | **Production Ready** |
| **MCP Server** | ✅ Fully Working | ✅ Fully Working | **Production Ready** |
| **NPM Published** | 🔧 In Progress | N/A | Development testing |
### **Important: Canvas and MCP Server Run Separately**
This system consists of **two independent components**:
1. **Canvas Server** - Runs the live Excalidraw canvas (web interface)
2. **MCP Server** - Connects to Claude Desktop/Claude Code/Cursor IDE
**You can choose any combination:**
- Canvas: Local OR Docker
- MCP Server: Local OR Docker
Both local and Docker setups are **fully working** and production-ready!
## 🚀 What This System Does
- **🎨 Live Canvas**: Real-time Excalidraw canvas accessible via web browser
- **🤖 AI Integration**: MCP server allows AI agents (like Claude) to create visual diagrams
- **⚡ Real-time Sync**: Elements created via MCP API appear instantly on the canvas
- **🔄 WebSocket Updates**: Live synchronization across multiple connected clients
- **🏗️ Production Ready**: Clean, minimal UI suitable for end users
## 🎥 Demo Video
> **See MCP Excalidraw in Action!**
[](https://youtu.be/RRN7AF7QIew)
*Watch how AI agents create and manipulate diagrams in real-time on the live canvas*
## 🏛️ Architecture Overview
### **Two Independent Components**
```
┌─────────────────────────────────────────────────────────────────┐
│ Component 1 │
│ 🎨 CANVAS SERVER │
│ (Runs Independently) │
│ │
│ ┌─────────────────┐ ┌─────────────────┐ │
│ │ Canvas Server │◀───────▶│ Frontend │ │
│ │ (src/server.js) │ │ (React + WS) │ │
│ │ Port 3000 │ │ Excalidraw UI │ │
│ └─────────────────┘ └─────────────────┘ │
│ │
│ 📍 Start: npm run canvas OR docker run (canvas) │
└─────────────────────────────────────────────────────────────────┘
▲
│ HTTP API
│ (Optional)
│
┌─────────────────────────────────────────────────────────────────┐
│ Component 2 │
│ 🤖 MCP SERVER │
│ (Runs Independently) │
│ │
│ ┌─────────────────┐ ┌─────────────────┐ │
│ │ AI Agent │◀───────▶│ MCP Server │ │
│ │ (Claude) │ │ (src/index.js) │ │
│ │ Desktop/Code │ stdio │ MCP Protocol │ │
│ └─────────────────┘ └─────────────────┘ │
│ │
│ 📍 Configure in: claude_desktop_config.json OR .mcp.json │
└─────────────────────────────────────────────────────────────────┘
🎯 Key Points:
• Canvas and MCP server are SEPARATE processes
• Canvas can run locally OR in Docker
• MCP server can run locally OR in Docker
• Canvas provides the visual interface (optional)
• MCP server connects Claude to the canvas (via HTTP API)
```
## 🌟 Key Features
### **Modern TypeScript Architecture**
- **Full TypeScript Migration**: Complete type safety for backend and frontend
- **Comprehensive Type Definitions**: Excalidraw elements, API responses, WebSocket messages
- **Strict Type Checking**: Enhanced development experience and compile-time error detection
- **Type-Safe React Components**: TSX components with proper props typing
### **🎨 Mermaid Diagram Support (NEW!)**
- **Mermaid to Excalidraw**: Convert Mermaid diagrams directly to Excalidraw elements
- **MCP Tool Integration**: Use `create_from_mermaid` tool from Claude
- **Browser-based Conversion**: Leverages DOM access in the frontend for accurate rendering
- **Multiple Diagram Types**: Supports flowcharts, sequence diagrams, class diagrams, and more
- **Test Button**: Quick test functionality directly from the canvas UI
### **Real-time Canvas Integration**
- Elements created via MCP appear instantly on the live canvas
- WebSocket-based real-time synchronization
- Multi-client support with live updates
### **Production-Ready Interface**
- Clean, minimal UI with connection status
- Simple "Clear Canvas" functionality
- No development clutter or debug information
### **Comprehensive MCP API**
- **Element Creation**: rectangles, ellipses, diamonds, arrows, text, lines
- **Element Management**: update, delete, query with filters
- **Batch Operations**: create multiple elements in one call
- **Advanced Features**: grouping, alignment, distribution, locking
### **Robust Architecture**
- TypeScript-based Express.js backend with REST API + WebSocket
- React frontend with official Excalidraw package and TypeScript
- Dual-path element loading for reliability
- Auto-reconnection and error handling
## 📦 Installation & Setup
### **Step 1: Choose Your Canvas Server Setup**
The canvas server provides the live Excalidraw interface.
#### **Option A: Local Canvas Server**
1. **Clone and Install**
```bash
git clone https://github.com/yctimlin/mcp_excalidraw.git
cd mcp_excalidraw
npm install
```
2. **Build the Project**
```bash
npm run build
```
3. **Start Canvas Server**
```bash
# Production mode (recommended)
npm run canvas
```
4. **Access the Canvas**
```
http://localhost:3000
```
#### **Option B: Docker Canvas Server**
**Option B1: Use Pre-built Image from GHCR** (Recommended)
```bash
docker pull ghcr.io/yctimlin/mcp_excalidraw-canvas:latest
docker run -d -p 3000:3000 --name mcp-excalidraw-canvas ghcr.io/yctimlin/mcp_excalidraw-canvas:latest
```
**Option B2: Build Locally**
```bash
git clone https://github.com/yctimlin/mcp_excalidraw.git
cd mcp_excalidraw
docker build -f Dockerfile.canvas -t mcp-excalidraw-canvas .
docker run -d -p 3000:3000 --name mcp-excalidraw-canvas mcp-excalidraw-canvas
```
3. **Access the Canvas**
```
http://localhost:3000
```
---
### **Step 2: Configure MCP Server in Your IDE**
The MCP server connects your AI assistant (Claude) to the canvas. **Choose local OR Docker format** based on your preference.
#### **Setup Combinations**
You can mix and match any combination:
| Canvas Server | MCP Server | Status |
|---------------|------------|--------|
| ✅ Local | ✅ Local | Recommended |
| ✅ Local | ✅ Docker | Fully Working |
| ✅ Docker | ✅ Local | Fully Working |
| ✅ Docker | ✅ Docker | Fully Working |
Configuration examples are provided in the next section for:
- Claude Desktop
- Claude Code
- Cursor IDE
## 🔧 Available Scripts
| Script | Description |
|--------|-------------|
| `npm start` | Build and start MCP server (`dist/index.js`) |
| `npm run canvas` | Build and start canvas server (`dist/server.js`) |
| `npm run build` | Build both frontend and TypeScript backend |
| `npm run build:frontend` | Build React frontend only |
| `npm run build:server` | Compile TypeScript backend to JavaScript |
| `npm run dev` | Start TypeScript watch mode + Vite dev server |
| `npm run type-check` | Run TypeScript type checking without compilation |
| `npm run production` | Build + start in production mode |
## 🎯 Usage Guide
### **For End Users**
1. Open the canvas at `http://localhost:3000`
2. Check connection status (should show "Connected")
3. AI agents can now create diagrams that appear in real-time
4. Use "Clear Canvas" to remove all elements
### **For AI Agents (via MCP)**
The MCP server provides these tools for creating visual diagrams:
#### **Basic Element Creation**
```javascript
// Create a rectangle
{
"type": "rectangle",
"x": 100,
"y": 100,
"width": 200,
"height": 100,
"backgroundColor": "#e3f2fd",
"strokeColor": "#1976d2",
"strokeWidth": 2
}
```
#### **Create Text Elements**
```javascript
{
"type": "text",
"x": 150,
"y": 125,
"text": "Process Step",
"fontSize": 16,
"strokeColor": "#333333"
}
```
#### **Create Arrows & Lines**
```javascript
{
"type": "arrow",
"x": 300,
"y": 130,
"width": 100,
"height": 0,
"strokeColor": "#666666",
"strokeWidth": 2
}
```
#### **Batch Creation for Complex Diagrams**
```javascript
{
"elements": [
{
"type": "rectangle",
"x": 100,
"y": 100,
"width": 120,
"height": 60,
"backgroundColor": "#fff3e0",
"strokeColor": "#ff9800"
},
{
"type": "text",
"x": 130,
"y": 125,
"text": "Start",
"fontSize": 16
}
]
}
```
## 🔌 MCP Server Configuration for IDEs
### **Prerequisites**
✅ Ensure your **canvas server is running** (from Step 1):
- Local: `npm run canvas`
- Docker: `docker run -d -p 3000:3000 mcp-excalidraw-canvas`
Canvas should be accessible at http://localhost:3000
### **Quick Reference**
Choose your configuration based on IDE and preference:
| IDE | Config File | Format Options |
|-----|-------------|----------------|
| **Claude Desktop** | `claude_desktop_config.json` | Local ⭐ / Docker ✅ |
| **Claude Code** | `.mcp.json` (project root) | Local ⭐ / Docker ✅ |
| **Cursor** | `.cursor/mcp.json` | Local ⭐ / Docker ✅ |
⭐ = Recommended | ✅ = Fully Working
---
## **Configuration for Claude Desktop**
Edit your `claude_desktop_config.json` file:
### **Format 1: Local MCP Server** ⭐ Recommended
```json
{
"mcpServers": {
"excalidraw": {
"command": "node",
"args": ["/absolute/path/to/mcp_excalidraw/dist/index.js"],
"env": {
"EXPRESS_SERVER_URL": "http://localhost:3000",
"ENABLE_CANVAS_SYNC": "true"
}
}
}
}
```
**Important:** Replace `/absolute/path/to/mcp_excalidraw` with your actual installation path.
### **Format 2: Docker MCP Server** ✅ Fully Working
**Using Pre-built Image from GHCR** (Recommended):
```json
{
"mcpServers": {
"excalidraw": {
"command": "docker",
"args": [
"run",
"-i",
"--rm",
"--network", "host",
"-e", "EXPRESS_SERVER_URL=http://localhost:3000",
"-e", "ENABLE_CANVAS_SYNC=true",
"ghcr.io/yctimlin/mcp_excalidraw:latest"
]
}
}
}
```
**OR Build Locally**:
```bash
cd mcp_excalidraw
docker build -f Dockerfile -t mcp-excalidraw .
```
Then use `mcp-excalidraw` as the image name in the configuration above.
---
## **Configuration for Claude Code**
Create or edit `.mcp.json` in your project root:
### **Format 1: Local MCP Server** ⭐ Recommended
```json
{
"mcpServers": {
"excalidraw": {
"command": "node",
"args": ["/absolute/path/to/mcp_excalidraw/dist/index.js"],
"env": {
"EXPRESS_SERVER_URL": "http://localhost:3000",
"ENABLE_CANVAS_SYNC": "true"
}
}
}
}
```
**Important:** Replace `/absolute/path/to/mcp_excalidraw` with your actual installation path.
### **Format 2: Docker MCP Server** ✅ Fully Working
**Using Pre-built Image from GHCR** (Recommended):
```json
{
"mcpServers": {
"excalidraw": {
"command": "docker",
"args": [
"run",
"-i",
"--rm",
"--network", "host",
"-e", "EXPRESS_SERVER_URL=http://localhost:3000",
"-e", "ENABLE_CANVAS_SYNC=true",
"ghcr.io/yctimlin/mcp_excalidraw:latest"
]
}
}
}
```
**OR Build Locally**:
```bash
cd mcp_excalidraw
docker build -f Dockerfile -t mcp-excalidraw .
```
Then use `mcp-excalidraw` as the image name in the configuration above.
### **Alternative: Using Claude CLI**
```bash
# Project-scoped (recommended)
claude mcp add --scope project --transport stdio excalidraw \
-- docker run -i --rm --network host \
-e EXPRESS_SERVER_URL=http://localhost:3000 \
-e ENABLE_CANVAS_SYNC=true \
mcp-excalidraw
# User-scoped (available across all projects)
claude mcp add --scope user --transport stdio excalidraw \
-- docker run -i --rm --network host \
-e EXPRESS_SERVER_URL=http://localhost:3000 \
-e ENABLE_CANVAS_SYNC=true \
mcp-excalidraw
```
---
## **Configuration for Cursor IDE**
Edit `.cursor/mcp.json`:
### **Format 1: Local MCP Server** ⭐ Recommended
```json
{
"mcpServers": {
"excalidraw": {
"command": "node",
"args": ["/absolute/path/to/mcp_excalidraw/dist/index.js"],
"env": {
"EXPRESS_SERVER_URL": "http://localhost:3000",
"ENABLE_CANVAS_SYNC": "true"
}
}
}
}
```
### **Format 2: Docker MCP Server** ✅ Fully Working
**Using Pre-built Image from GHCR** (Recommended):
```json
{
"mcpServers": {
"excalidraw": {
"command": "docker",
"args": [
"run",
"-i",
"--rm",
"--network", "host",
"-e", "EXPRESS_SERVER_URL=http://localhost:3000",
"-e", "ENABLE_CANVAS_SYNC=true",
"ghcr.io/yctimlin/mcp_excalidraw:latest"
]
}
}
}
```
**OR Build Locally**:
```bash
cd mcp_excalidraw
docker build -f Dockerfile -t mcp-excalidraw .
```
Then use `mcp-excalidraw` as the image name in the configuration above.
---
## **Important Configuration Notes**
| Setting | Purpose | Required |
|---------|---------|----------|
| `EXPRESS_SERVER_URL` | Canvas server URL | Yes (default: http://localhost:3000) |
| `ENABLE_CANVAS_SYNC` | Enable real-time canvas sync | Yes (set to "true") |
| `--network host` | Docker access to localhost | Required for Docker |
| `-i` flag | Interactive stdin/stdout | Required for Docker |
**Canvas is optional**: The MCP server works without the canvas in API-only mode (for programmatic access only).
## 🛠️ Environment Variables
| Variable | Default | Description |
|----------|---------|-------------|
| `EXPRESS_SERVER_URL` | `http://localhost:3000` | Canvas server URL for MCP sync |
| `ENABLE_CANVAS_SYNC` | `true` | Enable/disable canvas synchronization |
| `LOG_FILE_PATH` | `excalidraw.log` | Path to the log file |
| `DEBUG` | `false` | Enable debug logging |
| `PORT` | `3000` | Canvas server port |
| `HOST` | `localhost` | Canvas server host |
## 📊 API Endpoints
The canvas server provides these REST endpoints:
| Method | Endpoint | Description |
|--------|----------|-------------|
| `GET` | `/api/elements` | Get all elements |
| `POST` | `/api/elements` | Create new element |
| `PUT` | `/api/elements/:id` | Update element |
| `DELETE` | `/api/elements/:id` | Delete element |
| `POST` | `/api/elements/batch` | Create multiple elements |
| `GET` | `/health` | Server health check |
## 🎨 MCP Tools Available
### **Element Management**
- `create_element` - Create any type of Excalidraw element
- `update_element` - Modify existing elements
- `delete_element` - Remove elements
- `query_elements` - Search elements with filters
### **Batch Operations**
- `batch_create_elements` - Create complex diagrams in one call
### **Element Organization**
- `group_elements` - Group multiple elements
- `ungroup_elements` - Ungroup element groups
- `align_elements` - Align elements (left, center, right, top, middle, bottom)
- `distribute_elements` - Distribute elements evenly
- `lock_elements` / `unlock_elements` - Lock/unlock elements
### **Resource Access**
- `get_resource` - Access scene, library, theme, or elements data
## 🏗️ Development Architecture
### **Frontend** (`frontend/src/`)
- **React + TypeScript**: Modern TSX components with full type safety
- **Vite Build System**: Fast development and optimized production builds
- **Official Excalidraw**: `@excalidraw/excalidraw` package with TypeScript types
- **WebSocket Client**: Type-safe real-time element synchronization
- **Clean UI**: Production-ready interface with proper TypeScript typing
### **Canvas Server** (`src/server.ts` → `dist/server.js`)
- **TypeScript + Express.js**: Fully typed REST API + static file serving
- **WebSocket**: Type-safe real-time client communication
- **Element Storage**: In-memory with comprehensive type definitions
- **CORS**: Cross-origin support with proper typing
### **MCP Server** (`src/index.ts` → `dist/index.js`)
- **TypeScript MCP Protocol**: Type-safe Model Context Protocol implementation
- **Canvas Sync**: Strongly typed HTTP requests to canvas server
- **Element Management**: Full CRUD operations with comprehensive type checking
- **Batch Support**: Type-safe complex diagram creation
### **Type System** (`src/types.ts`)
- **Excalidraw Element Types**: Complete type definitions for all element types
- **API Response Types**: Strongly typed REST API interfaces
- **WebSocket Message Types**: Type-safe real-time communication
- **Server Element Types**: Enhanced element types with metadata
## 🐛 Troubleshooting
### **Canvas Not Loading**
- Ensure `npm run build` completed successfully
- Check that `dist/index.html` and `dist/frontend/` directory exist
- Verify canvas server is running on port 3000
- Check if port 3000 is already in use: `lsof -i :3000` (macOS/Linux) or `netstat -ano | findstr :3000` (Windows)
### **Elements Not Syncing**
- Confirm canvas server is running and accessible at http://localhost:3000
- Check `ENABLE_CANVAS_SYNC=true` in MCP server environment configuration
- Verify `EXPRESS_SERVER_URL` points to correct canvas server URL
- Check browser console for WebSocket connection errors
- For Docker: Ensure `--network host` flag is used
### **WebSocket Connection Issues**
- Check browser console for WebSocket errors (F12 → Console tab)
- Ensure no firewall blocking WebSocket connections on port 3000
- Try refreshing the browser page
- Verify canvas server is running: `curl http://localhost:3000/health`
### **Docker Issues**
**Canvas Container:**
- Check if container is running: `docker ps | grep canvas`
- View logs: `docker logs mcp-excalidraw-canvas`
- Ensure port 3000 is not already in use
**MCP Container:**
- For Docker MCP server, ensure `--network host` is used (required to access localhost:3000)
- Verify `-i` flag is present (required for MCP stdin/stdout protocol)
- Check environment variables are properly set
### **Build Errors**
- Delete `node_modules` and `dist/` directories, then run `npm install && npm run build`
- Check Node.js version (requires 16+): `node --version`
- Run `npm run type-check` to identify TypeScript issues
- Verify `dist/` directory contains both `index.js`, `server.js`, and `frontend/` after build
### **NPM Package Issues**
- **Status**: NPM package is under development
- **Recommendation**: Use local or Docker installation methods for production use
## 📋 Project Structure
```
mcp_excalidraw/
├── frontend/
│ ├── src/
│ │ ├── App.tsx # Main React component (TypeScript)
│ │ └── main.tsx # React entry point (TypeScript)
│ └── index.html # HTML template
├── src/ (TypeScript Source)
│ ├── index.ts # MCP server (TypeScript)
│ ├── server.ts # Canvas server (Express + WebSocket, TypeScript)
│ ├── types.ts # Comprehensive type definitions
│ └── utils/
│ └── logger.ts # Logging utility (TypeScript)
├── dist/ (Compiled Output)
│ ├── index.js # Compiled MCP server
│ ├── server.js # Compiled Canvas server
│ ├── types.js # Compiled type definitions
│ ├── utils/
│ │ └── logger.js # Compiled logging utility
│ └── frontend/ # Built React frontend
├── tsconfig.json # TypeScript configuration
├── vite.config.js # Vite build configuration
├── package.json # Dependencies and scripts
└── README.md # This file
```
## 🔮 Development Roadmap
- ✅ **TypeScript Migration**: Complete type safety for enhanced development experience
- ✅ **Docker Deployment**: Both Canvas and MCP server fully working in Docker
- 🔧 **NPM Package**: Resolving MCP tool registration issues
- 🎯 **Enhanced Features**: Additional MCP tools and capabilities
- 🎯 **Performance Optimization**: Real-time sync improvements
- 🎯 **Advanced TypeScript Features**: Stricter type checking and advanced type utilities
- 🎯 **Container Registry**: Publishing to GitHub Container Registry (GHCR)
## 🤝 Contributing
We welcome contributions! If you're experiencing issues with the NPM package or Docker version, please:
1. Fork the repository
2. Create a feature branch (`git checkout -b feature/amazing-feature`)
3. Commit your changes (`git commit -m 'Add amazing feature'`)
4. Push to the branch (`git push origin feature/amazing-feature`)
5. Open a Pull Request
## 📝 License
This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.
## 🙏 Acknowledgments
- **Excalidraw Team** - For the amazing drawing library
- **MCP Community** - For the Model Context Protocol specification
