splitwise-mcp

An MCP server that connects an AI assistant to Splitwise, a service for recording shared expenses and calculating who owes whom.

In plain words
What is it for?
Use it to view or manage expenses, groups, friends, and balances, including adding, editing, or deleting expenses.
Why use it?
It removes the need to manage Splitwise expenses and groups through separate manual API requests.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/chrischall/splitwise-mcp/splitwise-mcp
Any agent
npx skills add chrischall/splitwise-mcp --skill splitwise-mcp
Clone the repo
git clone --depth 1 https://github.com/chrischall/splitwise-mcp

Made for: Claude Code, Codex.

Per session 109 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,711 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00109 $0.01711
Opus 5 $0.00055 $0.00856
Sonnet 5 $0.00022 $0.00342
Haiku 4.5 $0.00011 $0.00171

Measured 2d ago against content hash d4af2bcf0022, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

splitwise-mcp scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/splitwise-mcp/SKILL.md · 162 lines

How it starts

The opening of the file, as written. The whole thing — 162 lines — stays where its author put it; the contents beside it link to each section on GitHub.

splitwise-mcp

MCP server for Splitwise — natural-language expense and group management via the Splitwise API.

Setup

Option A — npx (recommended)

Add to .mcp.json in your project or ~/.claude/mcp.json:

{
  "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
cd splitwise-mcp
npm install && npm run build

Then add to .mcp.json:

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

Or use a .env file in the project directory with SPLITWISE_API_KEY=<value>.

Getting your API key

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

Authentication

API key auth — no login flow or token rotation. The key is attached to every request as Authorization: Bearer <key>.

Tools

User

Tool Description
sw_get_current_user Get the authenticated user's profile (id, first_name, last_name, email)

Groups

Tool Description
sw_list_groups List all groups with id, name, and members[]
sw_get_group(id) Get a single group's details including members and balances
sw_create_group(name, group_type?, simplify_by_default?) Create a new group (group_type: apartment, house, trip, other)
sw_add_user_to_group(group_id, user_id?) Add a user by user_id (preferred) or first_name + last_name + email
sw_remove_user_from_group(group_id, user_id) Remove a user from a group

Read the full file on GitHub · 162 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 162 lines · 109 tokens per session scan A d4af2bcf0022

Subscribe to this mod's changes

splitwise-mcp is a skill published in the GitHub repository chrischall/splitwise-mcp (1 stars, last pushed 2d ago), licensed MIT. It adds 109 tokens to every session and 1,711 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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