gnucash-mcp

Free, open-source accounting software that works with the LLM.

Talk to your GnuCash books through Claude (or any AI assistant that supports MCP). Ask "how am I doing this month," dictate your transactions out loud, hand over the books for the AI to keep up while you focus on running your life or your business.

Your data stays on your machine. Your audit log stays on your machine. Nothing is uploaded anywhere — the AI reads and writes your local GnuCash file, and that's it.

Two real, populated sample books ship in this repo so you can try it before you commit anything. They're realistic — full years of activity, mixed currencies, customers, invoices, budgets, the works. Walk through one in five minutes; if it clicks, point the server at your own book and you're done.

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What does it look like?

This is what your AI assistant sees when it opens one of the sample books — a complete financial dashboard in a single call:

Book: samples/alex-chen-morales.gnucash
Currency: USD
Data range: 2025-01-01 to 2026-05-31
Last entry: 2026-05-31 (future-dated, 31 days ahead)
Warnings:
  ⚠ Past due invoice: Berlin Digital GmbH 58 days past 30-day default, EUR 4,200 (no term set)
  ⚠ Stale price: GBP last updated 150 days ago
Accounts: 108 total
Assets: 12 accounts, USD 602680.49
  Condo: USD 473250.00
  VTSAX: 230.7620 VTSAX @ 170.99 (USD 39457.99)
  Vehicle: USD 27845.00
  401k: USD 13404.62
  Checking Account: USD 12393.11
  ...
Liabilities: 4 accounts, USD 418457.79
  Credit cards (2): USD 38044.26
  Loans (2): USD 380413.53
  Top 3: Mortgage USD 372199.55, Chase Sapphire USD 22383.23, Business Amex USD 15661.03
Receivables: 3 accounts, USD 10246.46
  Accounts Receivable EUR: USD 4908.96
  Accounts Receivable: USD 3500.00
  Accounts Receivable CAD: USD 1837.50
Reconciliation:
  Checking Account: 174 splits unreconciled since 2025-12-30 (4 months behind) ⚠
  7 accounts never reconciled ⚠
Net worth trajectory:
  12mo ago: USD 187,925
   6mo ago: USD 180,614
   3mo ago: USD 191,350
   1mo ago: USD 185,444
       now: USD 184,223
Monthly net (last 6 months):
  Apr 2026 (MTD): -9,056
  Mar 2026: +3,092
  Feb 2026: +5,202
  Jan 2026: +1,086
  Dec 2025: +4,853
  Nov 2025: -1,494
Runway: 121 days (USD 84,579 liquid / USD 694/day burn)
Budget (2026 Annual Budget): 41% used / 33% elapsed (+8% over pace)
Transactions: 2473
Scheduled: 13 recurring, none due in next 7 days
Business: 4 customers, 2 vendors, 1 employee

That's not a screenshot — that's the AI's actual orientation view. Net worth trajectory, runway, budget pacing, who owes you money, what's overdue, what hasn't been reconciled. One call, and your assistant has the full picture before you've even finished saying hello.

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Who is this for?

• Personal finance people who keep their books in GnuCash and want to dictate transactions, ask their assistant where the money's going, get reconciliation help, plan budgets.
• Small business owners who run their books in GnuCash and want to issue invoices, track receivables, see vendor spending, manage cash flow without leaving the conversation.
• People who care that their data stays local. No cloud sync. No SaaS. Your .gnucash file is the system of record; this just gives your AI a way to read and write it the way GnuCash itself does.

You don't need to be a developer. You need:

• A computer (Mac, Windows, or Linux)
• GnuCash itself, or willingness to install it (free at gnucash.org)
• An AI assistant that supports MCP (Claude Desktop is the most common; Claude Code, Continue.dev, and others work too)
• 10 minutes to get the sample books running, then another 10 to point at your own

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Try it without risking anything

The repo ships two sample books — fully-populated synthetic ledgers you can talk to without touching your real data. Pick one, point the server at it, and start asking questions.

samples/alex-chen-morales.gnucash — Personal + freelance

A Seattle-based independent software contractor with a US LLC. USD-default. ~141 accounts, ~2,475 transactions across 2025– 2026. Has a mortgage, a brokerage with VTSAX/VBTLX/AAPL/MSFT/ETH holdings, a 401(k), four customers spanning USD/EUR/GBP/CAD with foreign-currency invoices, scheduled bills, a budget — pretty much everything the server can do, all in one book.

samples/lin-wei.gnucash — Cross-border small business

A Shenzhen-based small-business owner running a cross-border e-commerce operation. CNY-default. ~105 accounts, ~1,960 transactions. Chinese-named customers paying in CNY, USD/EUR customers paying in foreign currency with realized FX gain/loss on rate moves, domestic Chinese investments (茅台, 宁德时代, ETFs), an LPR-based mortgage, mixed payment rails (checking + Alipay + WeChat Pay).

Both books are fictional. See samples/README.md for the full breakdown of what's in each.

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Quick Start (5 minutes)

1. Install

git clone https://github.com/ninetails-io/gnucash-mcp.git
cd gnucash-mcp

Then either:

uv sync                # if you have uv (recommended)
# or
pip install -e .       # if you have pip

If you don't have uv, install it with one line: curl -LsSf https://astral.sh/uv/install.sh | sh

2. Make a working copy of a sample book

The server writes audit logs and auto-backups alongside the book file. You don't want either of those committed back to the repo, so copy the book somewhere outside the repo first:

mkdir -p ~/gnucash-mcp-scratch
cp samples/alex-chen-morales.gnucash ~/gnucash-mcp-scratch/alex.gnucash

3. Tell Claude Desktop about the server

Find your Claude Desktop config:

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

Add this (replace the two paths with your actual paths):

{
  "mcpServers": {
    "gnucash": {
      "command": "uv",
      "args": [
        "run",
        "--directory",
        "/path/to/gnucash-mcp",
        "python",
        "-m",
        "gnucash_mcp",
        "--modules=all"
      ],
      "env": {
        "GNUCASH_BOOK_PATH": "/Users/yourname/gnucash-mcp-scratch/alex.gnucash"
      }
    }
  }
}

Quit Claude Desktop completely (not just close the window — quit) and reopen it. Look for the hammer 🔨 icon next to the text input. That means the server's connected.

4. Try it

Ask Claude:

• "Summarize the book."
• "What's my net worth been doing?"
• "Show me anyone who owes me money."
• "What did I spend on dining last month?"
• "Set a $500 monthly grocery budget."

The first response usually starts with the dashboard from above. Everything after that is conversational.

When you're ready to point at your own book, replace the GNUCASH_BOOK_PATH value with the path to your real .gnucash file (more on that next), restart Claude Desktop, and ask away.

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Connecting to your own book

One-time conversion: GnuCash file format

The server only reads the SQLite form of GnuCash files, not the older XML form. To convert:

1. Open your book in GnuCash itself
2. File → Save As
3. Change "Data Format" to SQLite3
4. Save with a new filename (e.g. mybook-sqlite.gnucash)
5. Keep the XML original as a backup.

You only do this once. From then on, GnuCash and the MCP server both work against the same SQLite file.

Set the path

Update GNUCASH_BOOK_PATH in your Claude Desktop config to point at your own SQLite-format book. Restart Claude Desktop.

Use absolute paths, not ~ or relative paths. On Mac/Linux: /Users/yourname/Documents/mybook.gnucash. On Windows: C:\\Users\\yourname\\Documents\\mybook.gnucash (note the doubled backslashes — that's a JSON requirement).

Other AI clients

This is an MCP server, so it works with any client that speaks MCP. Notes for non–Claude Desktop clients:

• Claude Code: claude mcp add-json gnucash '{"command":"uv","args":["run","--directory","/path/to/gnucash-mcp","python","-m","gnucash_mcp","--modules=all"],"env":{"GNUCASH_BOOK_PATH":"/path/to/your/book.gnucash"}}' Add --scope user for all projects, --scope project for this one only.
• Anything else: set GNUCASH_BOOK_PATH and run uv run gnucash-mcp (or gnucash-mcp if installed via pip).

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What you can ask it to do

A non-exhaustive tour. Phrase any of these naturally — the assistant translates.

Recording activity

"I spent $47.50 at Safeway today on groceries, paid with my Visa."

Recorded: $47.50 from Credit Card:Visa to Expenses:Groceries on Apr 30, 2026. Description: "Safeway".

Setting up recurring bills

"Set up my rent as a recurring bill. $1,850 on the 1st of every month from checking."

Created scheduled transaction "Monthly Rent": $1,850 monthly, from Assets:Checking to Expenses:Rent. Next due: May 1, 2026.

Investment tracking

"I bought $1,000 of VTSAX at $170.99/share in my 401(k)."

Recorded VTSAX purchase: 5.85 shares at $170.99/share. Cost basis: $1,000.00. Lot created for capital-gains tracking when you eventually sell.

Invoicing customers

"Create a customer called Acme Corp and invoice them $1,500 for consulting."

Created customer Acme Corp (id 000005) and invoice 000019: 1× Consulting at $1,500.00 = $1,500.00. Open. Tell me when you're ready to post it.

Foreign-currency invoicing

"Invoice Berlin Digital €4,200 for Q1 retainer, due in 30 days."

Created EUR invoice 000020 for Berlin Digital GmbH: 1× Q1 Retainer at EUR 4,200 = EUR 4,200. Net 30. When they pay, I'll book the realized exchange-rate gain/loss to your FX account automatically.

Asking questions

"How much did I spend with each vendor this year?"

Office Depot: $2,340 (4 bills, $0 outstanding) CloudHost Inc: $1,200 (2 bills, $600 outstanding) Legal Associates: $3,500 (1 bill, $3,500 outstanding) Total billed $7,040 / paid $2,940 / outstanding $4,100.

Reconciliation

"Help me reconcile checking against the April statement."

[Walks you through it: pulls unreconciled splits, asks you to confirm cleared transactions, computes the running balance, marks the matched ones reconciled, leaves the mismatches for you to investigate.]

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Privacy and safety

Your data does not leave your machine. This server is a local process that reads and writes a local file. The AI assistant you're talking to (Claude Desktop, etc.) sees the results of your tool calls — the same content you'd see on screen — but the file itself stays where it always was.

Every write is logged. A human-readable audit trail lives alongside your book file at <your-book>.gnucash.mcp/audit/, one log file per day. You can read it at any time to see exactly what changed and when. Sample entry:

2026-04-30 14:32  POST INVOICE  id:000019
    total: 1500.00  date: 2026-04-30
    account: Assets:Accounts Receivable  txn:a1b2c3d4

Automatic backups. Before the very first write of each session, the server snapshots your book to <your-book>.gnucash.mcp/backups/ — so if something goes wrong, you can roll back to a known-good state without relying on Time Machine or your own habit. Backups are verified with PRAGMA integrity_check before being declared valid. See docs/RESTORE_FROM_BACKUP.md for the rollback procedure.

Reconciled splits are protected. The server refuses to delete or modify reconciled splits without an explicit override, so a careless prompt can't quietly invalidate your last bank reconciliation.

Voiding ≠ deleting. When you tell the AI to "void this transaction," it uses GnuCash's proper accounting void — preserving the transaction for the audit trail with values zeroed. Deletion is the destructive option; the AI will tell you which one it's doing.

Disclaimer: This software is provided "as is" under the MIT License, without warranty of any kind. The authors are not liable for any data loss, corruption, or financial discrepancy arising from its use. You are solely responsible for maintaining your own backups and verifying the accuracy of your books.

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Limiting what the AI can see

By default the server exposes its full toolset (87 tools as of v1.2.1). Each tool's description lives in the AI's system prompt, which costs context on every message. If you only use some features — say, no investments and no business module — you can tell the server to load only those modules:

"args": [
  "run", "--directory", "/path/to/gnucash-mcp",
  "python", "-m", "gnucash_mcp",
  "--modules=core,reporting,budgets,scheduling"
]

Module	What it gives you
core	Accounts, transactions, the dashboard. Always loaded.
reconciliation	Bank reconciliation, void/unvoid
reporting	Spending, income, balance sheet, net worth, cash flow, debt payoff
budgets	Create budgets, set targets, track variance
scheduling	Recurring transactions, upcoming bills
investments	Stocks, mutual funds, lots, capital-gain tracking
business	Customers, vendors, employees, invoices, bills, payments
admin	Account-level metadata (APR, credit limit, etc.)
backup	Manual snapshot tools

Use --modules=all to load everything (the default for the sample-book quickstart above), or list a subset to keep your context light. You can also set GNUCASH_MCP_MODULES=core,reporting as an environment variable instead.

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What's in v1.2.1

This release is the long-tail completion of the v1.2 business- module promise — what v1.2 should have been at first ship, plus a generous correctness sweep on every non-USD-default path the test books surfaced.

Major:

• Multi-currency, end-to-end. Foreign-currency invoices post and pay against the right exchange rates from your price table; rate drift between post-date and pay-date is recognized as realized FX gain/loss in a dedicated income account (or one you specify).
• A complete first-call dashboard. get_book_summary now shows net-worth trajectory, runway, monthly net income, budget pacing, reconciliation backlog with split counts, upcoming bills, and warnings — turning the LLM's first call from "what is the state of the books" into "what do I need to do next."
• Customer / vendor / employee CRUD complete. Create, list, get, update (new in 1.2.1), and delete. No more needing to open GnuCash itself just to fix a typo on an address.
• Posting workflow lifecycle complete. post_invoice and pay_invoice joined by unpost_invoice (new) so a posted invoice can be reversed cleanly without SQL surgery. delete_transaction refuses to break the lifecycle by removing posting records directly.
• Automatic backups. First write of each session snapshots the book; staged retention (7 session / 4 weekly / 6 monthly) keeps you covered without filling your disk.

Plus a thousand smaller fixes from intensive testing on two real-shape books — multi-currency reporting, debt-payoff amortization for mortgages, voided-payment handling, employee- expense-voucher hooks, and many more. See specs/NEXT_STEPS_1_3.md for the 1.3 roadmap (taxtables, jobs, credit notes, employee expense vouchers).

A condensed changelog of major releases lives in CHANGELOG.md.

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Troubleshooting

No 🔨 hammer icon, or "tool not found"

• Quit Claude Desktop completely, then reopen it. (Closing the window isn't enough — you have to quit the application.)
• Verify the paths in your config are absolute and correct.
• Check the JSON for trailing commas — they break the config silently.

"Book not found"

• Use absolute paths, not ~ or relative paths.
• Mac/Linux: /Users/yourname/Documents/book.gnucash
• Windows: C:\\Users\\yourname\\Documents\\book.gnucash (doubled backslashes — JSON requirement)

"Cannot open book" / piecash errors

• Confirm your book is in SQLite format, not XML.
• Make sure GnuCash isn't open with the same book — file lock.
• Try opening the book in GnuCash itself to verify it isn't corrupted.

"Account not found"

• Use full account paths: Expenses:Groceries, not just Groceries.
• Or ask the assistant to list accounts: "List my accounts."

Something went wrong

• Open the audit log at <your-book>.gnucash.mcp/audit/ — every write since the server first ran is there with before/after detail.
• If you need to roll back, docs/RESTORE_FROM_BACKUP.md walks through it.

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Support the project

If gnucash-mcp is useful to you, consider buying me a coffee. It helps keep development going.

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For developers

Contributor guide and design notes live in CLAUDE.md. Quick orientation:

uv sync --extra dev
uv run pytest                       # 1,044 tests as of v1.2.1
uv run ruff check src/ tests/
uv run black --check src/ tests/

The server is built on piecash (Python interface to GnuCash's SQLite books) and the MCP Python SDK. Roughly 18,000 lines of Python source, 20,000 lines of tests, modularized so disabled modules cost nothing at runtime.

License

MIT.

Acknowledgments

• GnuCash — the free, open-source accounting software this server makes conversational.
• piecash — Python interface to GnuCash SQLite books.
• MCP Python SDK — the Model Context Protocol implementation.