Splitwise MCP Server — Control Splitwise With Plain English

"Add a ₩45,000 dinner, I paid, split equally." Done. No app. No tapping. No math.

Why I Built This

I was about to head on a trip with friends and already dreading the expense tracking.

You know how it goes — someone pays for dinner, someone else grabs the cab, another person covers the hotel deposit. By day two, you've lost track. So you open Splitwise, tap through four screens, type the amount, select the people, pick who paid, hit save. Then do it again for the next thing. And the next.

I thought: I'm already using Claude for everything else. What if I could just tell it what happened, and it handles Splitwise for me?

So I built this over a weekend. It's a small Python server that connects Claude AI directly to your Splitwise account. You talk to Claude like a human, and it does the Splitwise work for you — adding expenses, checking balances, recording settlements, fixing mistakes.

No switching apps. No manual entry. Just say what happened.

What It Feels Like to Use

You:    "We had a group dinner for ₩65,000. I paid. Split equally."
Claude: Done! Added "Group dinner" for ₩65,000.00 (KRW), split equally
        among 4 members. Each person owes ₩16,250.

You:    "What does everyone owe in the trip group?"
Claude: Here are the current balances:
        • Raj owes you ₩32,500
        • Priya owes you ₩16,250
        • Sam is owed ₩8,000 by the group

You:    "Record that Raj paid me back ₩30,000."
Claude: Payment of ₩30,000 recorded. Raj's balance updated.

You:    "Wait, that dinner was actually ₩72,000. Can you fix it?"
Claude: Updated! "Group dinner" changed to ₩72,000. Shares recalculated.

Works with any currency Splitwise supports — USD, EUR, INR, KRW, JPY, and more.

How It Works (The Simple Version)

You talk to Claude
       ↓
Claude understands what you want
       ↓
Claude calls this MCP server
       ↓
This server calls the Splitwise API
       ↓
Your Splitwise account updates instantly
       ↓
Everyone's app reflects the change

MCP (Model Context Protocol) is a standard way to give Claude access to external tools. This project is the "Splitwise tool" — a bridge between Claude and your Splitwise account.

See architecture.md for a detailed diagram of how everything connects.

What You Can Do

All Available Tools

Project Structure

splitwise-mcp/
├── splitwise_server.py   ← The entire server (~500 lines, one file)
├── .env                  ← Your API key (never committed to git)
├── requirements.txt      ← Python dependencies
├── architecture.md       ← How everything connects
├── DEPLOY.md             ← How to host on a VPS
└── README.md             ← This file

Built With

• FastMCP — Python MCP framework
• Splitwise REST API v3
• httpx — HTTP client
• Hosted on Hostinger VPS (Ubuntu)

Built by a first-time Python developer who just wanted to stop manually logging trip expenses. If I can build it, you can use it.

Setup

What You'll Need

• Python 3.10+ (python3 --version to check)
• A Splitwise account + API key from secure.splitwise.com/apps
• Claude Desktop or Claude Code

Step 1: Clone and install

git clone https://github.com/yourusername/splitwise-mcp.git
cd splitwise-mcp
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

Step 2: Add your API key

Create a file called .env in the project folder:

SPLITWISE_API_KEY=paste_your_key_here

Where to get your key:

1. Go to secure.splitwise.com/apps
2. Click "Register your application"
3. Fill in any name (e.g., "My MCP Server")
4. Copy the API Key into your .env file

Step 3: Connect to Claude Desktop

Edit ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "splitwise": {
      "command": "/full/path/to/venv/bin/python3",
      "args": ["/full/path/to/splitwise_server.py"]
    }
  }
}

Restart Claude Desktop. You'll see a hammer icon — that means tools are connected.

Step 4 (Optional): Host on a Server for 24/7 Access

Want it running even when your laptop is off? Deploy to any VPS (I use Hostinger).

See DEPLOY.md for the full step-by-step guide.

Once hosted, connect Claude Desktop via:

{
  "mcpServers": {
    "splitwise": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "http://YOUR_SERVER_IP:8000/mcp", "--allow-http"]
    }
  }
}

Troubleshooting

License

MIT — use it however you like.