Splitwise Mcp

Splitwise MCP

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A Model Context Protocol server that connects Claude to Splitwise, giving you natural-language access to your expenses, groups, friends, and balances.

[!WARNING] AI-developed project. This codebase was entirely built and is actively maintained by Claude Code. No human has audited the implementation. Review all code and tool permissions before use.

What you can do

Ask Claude things like:

• "What do I owe?"
• "Add a $50 dinner expense to the vacation group"
• "Split this hotel bill 60/40 with Sarah"
• "Who's in the trip group?"
• "Add Sam to the household group"
• "Show me recent expenses"
• "Delete that duplicate expense"
• "Download the receipt from that hotel expense"
• "Add that Amazon order screenshot as the receipt on the water-jug expense"
• "Log $250.01 camp, Sam paid, split 50/50"
• "Find every 'example' expense this year, including deleted ones, and why they were deleted"

Requirements

• Claude Desktop or Claude Code
• Node.js 22 or later
• A Splitwise account and API key

Acknowledgement of Terms

By using this MCP server, you acknowledge and agree to the following:

1. This server accesses your own Splitwise account via Splitwise's official Developer API. Auth happens via your own API consumer key + secret, which Splitwise issues to you when you register an app. It does not — and cannot — access anyone else's expenses or groups.

2. Splitwise's Developer Terms govern your use of this server. The clauses most relevant here:

You will use Splitwise Materials solely as necessary to develop, test and support a Self-Service integration of your software application… with Splitwise.

And on rate limits: "You will not use the API in a manner that exceeds rate limits, or constitutes excessive or abusive usage." And on competitive use: "You may not [use] Splitwise Materials to create an application that replicates existing Splitwise functionality or competes with Splitwise."

You are agreeing to those terms — read by the maintainer 2026-05-23 — every time you invoke a tool in this server.

3. Personal, non-commercial use only. This project is not affiliated with, endorsed by, sponsored by, or in partnership with Splitwise, Inc. It is a personal automation tool that calls the documented public Splitwise REST API on your own account. Do not use it to commercialize Splitwise data, compete with Splitwise's product, or share API credentials with third parties.

4. Your API key is yours alone. Splitwise issues credentials per-app, per-developer. Do not commit your SPLITWISE_API_KEY (or consumer key/secret) to git, do not paste it into shared chats, and do not embed it in a public client.

5. You accept full responsibility for any consequences of using this server in connection with your Splitwise account — rate limiting, API key revocation, account warnings, or any enforcement action. If Splitwise objects to your use or your usage exceeds their rate limits, stop using this server.

This section is the maintainer's good-faith summary of the terms — it is not legal advice and does not modify or supersede Splitwise's actual Developer Terms.

Installation

Option A -- npx (recommended)

npx -y splitwise-mcp

Add to your Claude config (.mcp.json or Claude Desktop config):

{  "mcpServers": {    "splitwise": {      "command": "npx",      "args": ["-y", "splitwise-mcp"],      "env": {        "SPLITWISE_API_KEY": "your-api-key-here"      }    }  }}

Option B -- from source

git clone https://github.com/chrischall/splitwise-mcp.gitcd splitwise-mcpnpm installnpm run build

Add to Claude Desktop config:

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

{  "mcpServers": {    "splitwise": {      "command": "node",      "args": ["/absolute/path/to/splitwise-mcp/dist/index.js"],      "env": {        "SPLITWISE_API_KEY": "your-api-key-here"      }    }  }}

Getting your API key

1. Go to secure.splitwise.com/apps/register
2. Register an app (name and description can be anything)
3. Copy the API key from the app detail page

Credentials

Confirmations

Every Splitwise write (creating, editing or deleting expenses, groups, friends, comments, or your profile) notifies other people, so it asks you to confirm first. A client that can show a confirmation prompt (Claude Code) shows one (unless MCP_CONFIRM_ELICITATION=off). On a client that cannot (claude.ai, Claude Desktop), the first call changes nothing and returns a preview of exactly what will be sent plus a confirmToken; only a repeat call with that token goes through, and the token is refused if anything in the request changed in between.

To save calls on such a client: sw_confirm({confirmToken}) finishes any previewed write with the token alone (the server kept the arguments, so a receipt's bytes are not sent a second time), and sw_batch({ops}) previews and approves several expense/comment writes at once — e.g. create an expense, then comment on it and attach its receipt with refs: {"expense_id": "0.expense_id"}. A batch runs in order and stops at the first failure (no rollback; the result says what was applied).

Available tools

31 tools across 6 domains. All tools are prefixed sw_.

User

Groups

Friends

Expenses

Confirming

Receipts

Utilities

Troubleshooting

"SPLITWISE_API_KEY is required" -- set the environment variable in your MCP config or a .env file.

Attaching a receipt -- sw_create_expense, sw_update_expense and sw_attach_receipt take receipt: { base64, filename, mime_type? } (works everywhere, including a hosted server) or, on a local server with SPLITWISE_INPUT_DIR set, receipt: { path, filename } for a file inside that directory. PNG, JPEG, GIF or PDF up to 10 MiB (Splitwise documents no limit); the type is detected from the bytes, and a mime_type that disagrees is refused. The confirmation preview shows the file's name, type, size and SHA-256 instead of its contents, and the token is bound to those bytes. After the write the tool checks Splitwise actually stored the file (receipt.original) and returns an error naming the expense if it did not. A receipt replaces any receipt already on the expense.

401 when opening a receipt URL -- the receipt.original / receipt.large URLs on an expense are not public; they need the API key. Use sw_get_receipt instead of fetching them directly.

Receipt lands somewhere you can't read it -- sw_get_receipt writes to the server's filesystem, which is not the caller's when the server is hosted or containerised. Pass inline: true for the bytes (an image block for images, an embedded resource for PDFs) or extract_text: true for a PDF's text. With inline or extract_text and no output_dir, nothing is written unless you also pass write: true. Pass write: false to skip the write in any case; if it fails on its own (read-only filesystem), the call still succeeds and reports write_error as long as you asked for content.

429 rate limit -- Splitwise has undocumented rate limits. Wait a moment and retry.

Tools not appearing in Claude -- go to Claude Desktop > Settings > Developer to see connected servers. Make sure you fully quit and relaunched after editing the config.

Development

npm test        # tsc typecheck + run the test suite (vitest)npm run build   # compile TypeScript -> dist/

Project structure

src/  client.ts         Splitwise API client (auth, request handling)  index.ts          MCP server entry point  tools/    user.ts         sw_get_current_user, sw_get_user    healthcheck.ts  sw_healthcheck    groups.ts       group CRUD and membership    friends.ts      friend list and management    expenses.ts     expense CRUD    receipts.ts     authenticated receipt download + PDF text extraction    utilities.ts    notifications, categories, currencies, comments    _confirm.ts     confirmation gate shared by every write

License

MIT