Splitwise MCP Server

A standalone Model Context Protocol (MCP) server that provides complete access to the Splitwise API. Use it with Claude Desktop, VS Code Copilot, ChatGPT, or any MCP-compatible client to manage your Splitwise expenses through natural language.

Features

26 MCP Tools organized in 7 categories:

• 👤 User Management (3) - Profile and settings
• 👥 Group Management (7) - Create/manage expense groups
• 🤝 Friend Management (5) - Add/manage friends
• 💰 Expense Management (6) - Create/track expenses with custom splits
• 💬 Comments (3) - Comment on expenses
• 🔔 Notifications (1) - View account activity
• 🛠️ Utilities (2) - Currencies and categories

Supported Clients

• ✅ Claude Desktop (Anthropic's desktop app) - Uses stdio or WebSocket modes
• ✅ VS Code with GitHub Copilot (via splitwise-mcp-vscode extension)
• ✅ ChatGPT (with custom MCP integration)
• ✅ Any MCP-compatible client (stdio or WebSocket+HTTP modes)

Quick Start

1. Install Dependencies

npm install
npm run build

2. Get Splitwise Credentials

Visit secure.splitwise.com/apps and register your app:

• Name: My Splitwise MCP
• Homepage URL: http://localhost
• Callback URL: http://localhost:8080/callback

Save your Consumer Key and Consumer Secret.

3. Get Access Token

Run the token helper:

npm run get-token

Or manually:

1. Visit: https://secure.splitwise.com/oauth/authorize?client_id=YOUR_CONSUMER_KEY&response_type=code&redirect_uri=http://localhost:8080/callback
2. Authorize the app and copy the code from the redirect URL
3. Exchange for token:

curl -X POST "https://secure.splitwise.com/oauth/token" \
  -d "grant_type=authorization_code" \
  -d "code=YOUR_AUTH_CODE" \
  -d "client_id=YOUR_CONSUMER_KEY" \
  -d "client_secret=YOUR_CONSUMER_SECRET" \
  -d "redirect_uri=http://localhost:8080/callback"

4. Configure Environment

Create .env:

SPLITWISE_ACCESS_TOKEN=your_access_token_here

5. Choose Your Client

Option A: Claude Desktop (Recommended)

Edit your Claude Desktop config file:

• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Mac/Linux: ~/Library/Application Support/Claude/claude_desktop_config.json

WebSocket mode (requires the adapter or direct connection):

{
  "mcpServers": {
    "splitwise": {
      "command": "splitwise-mcp-server",
      "args": [],
      "env": {
        "SPLITWISE_ACCESS_TOKEN": "your_access_token_here",
        "PORT": "3002"
      }
    }
  }
}

Stdio mode (original, uses stdio transport):

{
  "mcpServers": {
    "splitwise": {
      "command": "splitwise-mcp-server",
      "args": ["--stdio"],
      "env": {
        "SPLITWISE_ACCESS_TOKEN": "your_access_token_here"
      }
    }
  }
}

Restart Claude Desktop and test:

"Show me my Splitwise friends"
"List my recent expenses"
"Create a $50 dinner expense split equally"

Option B: VS Code with GitHub Copilot

Install the Splitwise MCP VS Code Extension:

# Install the VS Code extension
code --install-extension splitwise-mcp-1.0.0.vsix

Configure your access token in VS Code settings, then use Copilot Chat:

"Show my Splitwise balance"
"Add a $30 grocery expense to my Roommates group"

See the VS Code extension README for detailed setup.

Option C: Custom MCP Client

The server uses stdio transport and follows the MCP specification. Connect any MCP client:

// Example: Using MCP SDK Client
import { Client } from '@modelcontextprotocol/sdk/client/index.js';
import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js';

const transport = new StdioClientTransport({
  command: 'splitwise-mcp-server',
  env: { SPLITWISE_ACCESS_TOKEN: 'your_token' }
});

const client = new Client({ name: 'my-client', version: '1.0.0' }, { capabilities: {} });
await client.connect(transport);
const tools = await client.listTools();

Available Tools

User Management

• splitwise_get_current_user - Get your profile info
• splitwise_get_user - Get another user's info
• splitwise_update_user - Update profile settings

Group Management

• splitwise_get_groups - List all groups
• splitwise_get_group - Get group details
• splitwise_create_group - Create new group
• splitwise_delete_group - Delete group
• splitwise_restore_group - Restore deleted group
• splitwise_add_user_to_group - Add member to group
• splitwise_remove_user_from_group - Remove member from group

Friend Management

• splitwise_get_friends - List all friends with balances
• splitwise_get_friend - Get friend details
• splitwise_add_friend - Add single friend
• splitwise_add_friends - Add multiple friends
• splitwise_remove_friend - Remove friend

Expense Management

• splitwise_get_expenses - List/filter expenses
• splitwise_get_expense - Get expense details
• splitwise_create_expense - Create expense (equal or custom split)
• splitwise_update_expense - Update expense
• splitwise_delete_expense - Delete expense
• splitwise_restore_expense - Restore deleted expense

Comments

• splitwise_get_comments - Get expense comments
• splitwise_add_comment - Add comment to expense
• splitwise_delete_comment - Delete comment

Notifications

• splitwise_get_notifications - Get recent activity

Utilities

• splitwise_get_currencies - Get supported currencies
• splitwise_get_categories - Get expense categories

Usage Examples

View balances:

"What do I owe each of my friends?"
"Show me my Splitwise balance"

Create expenses:

"Add a $60 grocery expense split equally in my Roommates group"
"I paid $100 for dinner - I owe $40, John owes $60"
"Create a $1200 monthly rent expense split equally"

Manage groups:

"Create a group called 'Vegas Trip' and add alice@email.com"
"Who's in my Apartment group?"
"Show me all expenses in the Weekend Getaway group"

Filter expenses:

"Show me restaurant expenses from last month"
"List all expenses over $100"
"What did I spend the most on this year?"

Troubleshooting

Authentication failed:

• Verify token in .env matches the one in claude_desktop_config.json
• No extra spaces or quotes around the token
• Token hasn't expired - regenerate with npm run get-token

Server not found:

• Use absolute path in config
• Windows: Use \\ (double backslashes)
• Run npm run build after code changes
• Path should point to dist/index.js not src/index.ts

Tools not appearing in Claude:

• Verify JSON syntax in claude_desktop_config.json
• Completely close and restart Claude Desktop (check system tray)
• Check Claude Desktop logs: Help → Show Logs

Authorization code expired:

• Codes expire in 10 minutes
• Get a new code and exchange immediately
• Use the token helper script to automate: npm run get-token

For detailed setup instructions, see SETUP.md

Server Modes

The Splitwise MCP server supports multiple deployment modes:

WebSocket Mode (Default)

npm run dev:ws
# or
PORT=4001 npm start

• Starts on port 4001 (configurable via PORT env var)
• Uses WebSocket + HTTP JSON-RPC protocol
• Recommended for production deployments
• Can be used with HTTP adapter for remote access

Stdio Mode

npm run dev:stdio
# or
npm start -- --stdio

• Uses standard input/output (classic MCP protocol)
• Good for direct client integration
• Default mode when --stdio flag is passed
• Recommended for Claude Desktop

HTTP Adapter Mode

npm run dev:adapter
# or in another terminal while WebSocket server is running:
WS_BACKEND_URL=ws://localhost:4001 npm run adapter

• Runs on port 4000 (configurable via PORT env var)
• Proxies HTTP/JSON-RPC requests to the WebSocket backend
• Provides HTTP endpoints for testing:
  • GET /health - Health check
  • GET /status - Backend connection status
  • GET /listTools - List available tools
  • POST /rpc - JSON-RPC request endpoint
  • POST / - Alternative JSON-RPC endpoint
  • WS / - WebSocket upgrade endpoint

Development

# Install dependencies
npm install

# Build TypeScript
npm run build

# Watch mode (auto-rebuild)
npm run watch

# WebSocket mode (default)
npm run dev:ws

# Stdio mode
npm run dev:stdio

# HTTP Adapter mode (in separate terminal with backend running)
npm run dev:adapter

# Get OAuth token
npm run get-token

Development & Running

Local Development

# Terminal 1: Start WebSocket backend
PORT=4001 npm run build
PORT=4001 npm run dev:ws

# Terminal 2: (Optional) Start HTTP adapter
PORT=4000 npm run dev:adapter

# Terminal 3: Test the server
curl http://localhost:4000/health
curl http://localhost:4000/listTools

With Claude Desktop (WebSocket)

1. Configure as shown in "Option A: Claude Desktop" above
2. Run the server: PORT=4001 npm start
3. Restart Claude Desktop

With Claude Desktop (Stdio)

1. Configure with --stdio flag as shown above
2. Run the server: npm start -- --stdio
3. Restart Claude Desktop

Project Structure

SplitwiseMCPServer/
├── src/
│   ├── index.ts              # Main MCP server (WebSocket + Stdio modes)
│   ├── http-adapter.ts       # HTTP adapter for WebSocket backend
│   ├── splitwise-client.ts   # Splitwise API wrapper
│   ├── tools.ts              # Tool definitions (26 tools)
│   └── get-token.ts          # OAuth helper script
├── dist/                      # Compiled output
├── .env                       # Your credentials (not in git)
├── package.json
└── tsconfig.json

API Reference

All tools follow the Splitwise API v3.0 specification: dev.splitwise.com

Base URL: https://secure.splitwise.com/api/v3.0
Authentication: OAuth 2.0 Bearer Token

Security

• Never commit .env to version control
• Keep your access token private
• Use environment variables for credentials
• Set proper file permissions: chmod 600 .env (Unix/Mac)

Requirements

• Node.js: 18+
• NPM: Latest
• Splitwise Account: Free or premium

License

MIT

Related

• Splitwise MCP VS Code Extension - Optional VS Code integration
• Splitwise API Documentation - Official API reference
• Model Context Protocol - MCP specification

Contributing

Contributions welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Submit a pull request

Support

• Issues: GitHub Issues
• Splitwise API: dev.splitwise.com
• MCP Docs: modelcontextprotocol.io

License

MIT License - see LICENSE file for details

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Built with: TypeScript 5.3, MCP SDK 1.20.1, Axios 1.6.0