Monzo Server

Python 3.11+ MCP License: MIT Code style: ruff

Give Claude AI read-only access to your Monzo bank account through the Model Context Protocol.

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Overview

This MCP server enables Claude to securely interact with your Monzo bank account, providing insights into your spending habits, account balances, and transaction history—all through natural conversation.

Key Features

Feature	Description
Account Overview	View all Monzo accounts (current, joint, Flex)
Balance Tracking	Real-time balance and daily spending
Transaction History	Browse up to 90 days of transactions
Smart Analysis	Detect subscriptions and frequent merchants
Savings Pots	Monitor your savings goals
Push Notifications	Send custom alerts to your Monzo app

Security First

• Read-only access — Cannot move money or modify account settings
• OAuth 2.0 — Industry-standard authentication
• Local tokens — Credentials never leave your machine
• Open source — Full transparency, audit the code yourself

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Architecture

┌─────────────────────────────────────────────────────────────────┐
│                        Claude AI                                 │
└─────────────────────────────────────────────────────────────────┘
                              │
                              │ MCP Protocol (stdio)
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│                     Monzo MCP Server                             │
│  ┌───────────────────────────────────────────────────────────┐  │
│  │                      FastMCP                               │  │
│  │  ┌─────────┐ ┌──────────────┐ ┌──────────┐ ┌───────────┐  │  │
│  │  │Accounts │ │ Transactions │ │ Analysis │ │   Pots    │  │  │
│  │  │  Tools  │ │    Tools     │ │  Tools   │ │  Tools    │  │  │
│  │  └────┬────┘ └──────┬───────┘ └────┬─────┘ └─────┬─────┘  │  │
│  └───────┼─────────────┼──────────────┼─────────────┼────────┘  │
│          └─────────────┴──────────────┴─────────────┘           │
│                              │                                   │
│                     ┌────────▼────────┐                         │
│                     │  Monzo Client   │                         │
│                     │  (async httpx)  │                         │
│                     └────────┬────────┘                         │
└──────────────────────────────┼──────────────────────────────────┘
                               │
                               │ HTTPS + Bearer Token
                               ▼
                    ┌─────────────────────┐
                    │    Monzo API        │
                    │  api.monzo.com      │
                    └─────────────────────┘

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Quick Start

Prerequisites

• Python 3.11+
• A Monzo account
• Claude Code CLI

1. Create a Monzo Developer App

1. Visit developers.monzo.com

2. Sign in and click "New OAuth Client"

3. Configure your app:

   Field	Value
   Name	Claude MCP (or anything you like)
   Redirect URL	http://localhost:8080/callback
   Confidentiality	Confidential

4. Save your Client ID and Client Secret

2. Install the Server

# Clone the repository
git clone https://github.com/yourusername/monzo-mcp.git
cd monzo-mcp

# Create virtual environment
python -m venv venv
source venv/bin/activate  # Windows: venv\Scripts\activate

# Install in development mode
pip install -e .

3. Configure Credentials

# Copy example configuration
cp .env.example .env

# Add your credentials to .env
MONZO_CLIENT_ID=oauth2client_xxxxx
MONZO_CLIENT_SECRET=mnzconf.xxxxx

4. Authenticate with Monzo

python scripts/auth.py

This opens your browser for Monzo login. After approving:

Important: Open your Monzo app within 5 minutes to approve the login request, otherwise you'll be limited to 90 days of transaction history.

5. Connect to Claude Code

Add to your Claude Code configuration (~/.claude.json or project .mcp.json):

{
  "mcpServers": {
    "monzo": {
      "command": "/path/to/monzo-mcp/venv/bin/python",
      "args": ["-m", "monzo_mcp.server"],
      "cwd": "/path/to/monzo-mcp"
    }
  }
}

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Available Tools

Account Tools

Tool	Parameters	Description
get_accounts	—	List all Monzo accounts with IDs
get_balance	account_id	Current balance, total balance, today's spending

Transaction Tools

Tool	Parameters	Description
list_transactions	account_id, limit?	Recent transactions (default: 20, max: 100)
get_transaction	transaction_id	Detailed info including merchant address

Analysis Tools

Tool	Parameters	Description
list_subscriptions	account_id	Detect recurring payments (Netflix, Spotify, etc.)
list_frequent_merchants	account_id, min_transactions?	Find merchants you visit often

Savings Tools

Tool	Parameters	Description
list_pots	account_id	All savings pots with balances and goals

Notification Tools

Tool	Parameters	Description
create_feed_item	account_id, title, body	Push notification to Monzo app

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Example Conversations

You: "What's my current balance?"

Claude: Uses get_accounts then get_balance

Your current account balance is £1,234.56. You've spent £45.20 today.

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You: "Show me my subscriptions"

Claude: Uses list_subscriptions

I found 4 recurring payments:

• Netflix: £15.99/month
• Spotify: £10.99/month
• iCloud: £2.99/month

Estimated monthly total: £29.97

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You: "Where do I spend the most money?"

Claude: Uses list_frequent_merchants

Your top merchants this month:

1. Tesco (12 transactions) - £156.78
2. TfL (8 transactions) - £42.50
3. Pret A Manger (6 transactions) - £31.20

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Project Structure

monzo-mcp/
├── src/monzo_mcp/
│   ├── __init__.py          # Package metadata
│   ├── server.py            # MCP server entry point
│   ├── monzo_client.py      # Async Monzo API client
│   ├── models.py            # Data classes & exceptions
│   ├── constants.py         # Configuration constants
│   ├── utils.py             # Shared utilities
│   ├── analysis.py          # Subscription detection logic
│   └── tools/
│       ├── __init__.py      # Tool registration
│       ├── accounts.py      # Account tools
│       ├── transactions.py  # Transaction tools
│       ├── analysis.py      # Analysis tools
│       ├── pots.py          # Pot tools
│       └── feed.py          # Feed/notification tools
├── scripts/
│   └── auth.py              # OAuth authentication flow
├── pyproject.toml           # Package configuration
├── .env.example             # Environment template
└── README.md

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Limitations

Limitation	Reason
90-day history	Monzo's Strong Customer Authentication (SCA) requirement
Personal use only	Monzo API terms prohibit public applications
Rate limits	API calls are throttled; avoid rapid requests
No money movement	Intentional design choice for security

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Troubleshooting

"Access token expired"

python scripts/auth.py

Re-authenticate and approve in the Monzo app.

"Rate limited"

Wait 5-10 minutes before making more requests.

"No transactions found"

Ensure you approved the login in your Monzo app within 5 minutes of authenticating.

Server won't start

Check that your virtual environment is activated and credentials are in .env.

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Development

# Install dev dependencies
pip install -e ".[dev]"

# Run linting
ruff check src/

# Run type checking
mypy src/

# Run tests
pytest

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Contributing

Contributions are welcome! 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

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License

This project is licensed under the MIT License - see the LICENSE file for details.

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Acknowledgments

• Monzo for their excellent API
• Anthropic for Claude and the MCP protocol
• FastMCP for the MCP server framework

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Made with ❤️ for the Claude + Monzo community