Tillbooks MCP Server

TILL

Trusted Independent Ledger Library. Swiss accounting your agent can actually use.

TILL is a free, open-source (MIT), local-first accounting app built for Switzerland. Your books live in a single SQLite file on your own machine. They never leave the country, because they never leave your laptop.

The difference is the interface. Most accounting software is a GUI with an AI button bolted on. TILL is built the other way around: an MCP server is a first-class interface, so an agent can post entries, categorize transactions, draft and chase invoices, prepare the MWST-Abrechnung, and answer "how did my quarter go" by talking to the ledger directly. A minimalist Studio gives you human oversight of everything the agent did. Agent and human share one ledger.

Status: pre-alpha. The engine, the MCP verbs and the Studio are built across the numbered capabilities. Nothing here is ready to keep real books yet. Do not run your business on it.

Why

Switzerland has accounting software. It does not have accounting software an agent can drive, and the open-source option (Gäld) is AGPL, which forecloses an open-core model. TILL is a clean-room MIT rebuild aimed at the things that actually make Swiss books Swiss:

• QR-bill (Swiss QR-Rechnung) with the structured-address standard
• Three MWST rates (8.1%, 3.8%, 2.6%) and the MWST-Abrechnung that falls out of them
• Kontenrahmen KMU seeded out of the box
• ISO 20022 (camt/pain) for banking
• de-CH and en from day one

The ledger is not negotiable

Posted entries are append-only and immutable. A correction is a reversing entry, never a destructive edit, exactly as real accounting works. Posting is idempotent: a double-post does not double-count. These are asserted in the test suite, not merely promised in a README.

Install and run

TILL is on npm as tillbooks (0.1.0, pre-alpha). Installing it globally puts the till command on your path:

npm install -g tillbooks
till help

To connect an MCP client such as Claude Desktop or Cursor, point it at the stdio server. No API key is needed:

{
  "mcpServers": {
    "tillbooks": {
      "command": "npx",
      "args": ["-y", "tillbooks", "mcp"]
    }
  }
}

The ledger is created at ~/.till/till.db; set TILL_DB_PATH to put it somewhere else. till up starts the Studio, the human oversight GUI.

To work on TILL itself, build it from a checkout:

npm install
npm run build            # tsc emits dist/
node bin/till.mjs help

CONTRIBUTING.md has the full dev setup, and the quickstart walks the same steps.

Documentation

• Quickstart : where TILL stands, and how it connects to your agent
• Run inside an agent : drive TILL over MCP with no machine of your own
• Self-hosting in under an hour : stand up a served instance
• Documentation : the product guides and capability reference
• Design : the design law this project builds to

Before you use it

TILL is pre-alpha and it keeps books. DISCLAIMER.md is worth two minutes: TILL is not tax advice, you stay responsible for your own filings, and you should not point it at real accounts yet.

Contributing

• CONTRIBUTING.md : how to run it, and the rules that are not negotiable
• CODE_OF_CONDUCT.md : how we treat each other
• SECURITY.md : report vulnerabilities privately to security@tillbooks.ch
• SUPPORT.md : where to ask questions

License

MIT, Copyright (c) 2026 Nomadik GmbH. See LICENSE.

TILL is an independent project. It is not affiliated with, endorsed by, or derived from bexio AG or any other accounting vendor. It is a clean-room implementation built from public documentation.