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The AccountsOS connector

Your books, inside
Claude and ChatGPT.

Ask the AI app you already use about your company, and get the answer from your real ledger. You choose what it can see and do, and every call is logged.

Connect your AI appStart free for 14 days

96 accounting tools over MCP. Works with Claude, ChatGPT and any MCP app.

Claude, with and without the connector

Claude on its own

  • Asks you to paste in your figures, or works from what you upload.
  • Knows tax rules from its training, for whichever year that was.
  • Starts from nothing about your company.
  • No record of what it looked at.

Claude with AccountsOS

  • Reads your live ledger: cash, invoices, bills, VAT and deadlines.
  • Looks up UK rules and rates from a checked library and returns the GOV.UK source.
  • Knows your year end, VAT scheme and filing dates.
  • Every call is logged in your AccountsOS audit log.

The same applies to ChatGPT and other AI apps.

Things you can ask

  • “How much cash do we have across our accounts?”
  • “Which invoices are overdue, and by how much?”
  • “What VAT do we owe this quarter?”
  • “When is our next Companies House deadline?”
  • “What is the dividend allowance this tax year?”

You stay in control

One company per key

An API key reaches one company and nothing else. Give it read, write or admin access, and revoke it in Settings at any time.

Sign in, no key to paste

In Claude and ChatGPT you sign in to AccountsOS instead. The connector can only see the companies your login can already see.

Every call logged

Each request is recorded with the time, the app, the tool and the outcome. See it at Settings, Audit log, AI actions.

Nothing filed without you

The connector reads and prepares. Filings and payments still wait for your yes inside AccountsOS.

More on how we protect your data on the security page.

Connect in a few minutes

Claude

Add AccountsOS as a connector in Claude and sign in.

ChatGPT

Install the Finn app in ChatGPT and sign in. Read-only.

Any MCP app

Cursor, Claude Code and other agents, with a scoped API key.

Step-by-step help: connect Claude or ChatGPT.

Questions people ask

What is the AccountsOS connector?

It links an AI app such as Claude or ChatGPT to your AccountsOS books using the Model Context Protocol (MCP). The app gets 96 accounting tools, so it can answer from your ledger instead of guessing.

Can the AI app change my books?

Only if you allow it. A read key cannot change anything. The ChatGPT app is read-only. Filings and payments always wait for your approval inside AccountsOS.

Can I see what it did?

Yes. Every call through the connector is in Settings, Audit log, AI actions, with the time, the app, the tool and the outcome. Any change it made links to the record it changed.

Is my data used to train AI?

No. Your books are used to do your work and nothing else. The data processing agreement lists every sub-processor.

Do I need AccountsOS to use it?

Tax rules, rates and Companies House lookups work without an account. Anything about your own books needs an AccountsOS account.

Give your AI app your real books

Free for 14 days, no card. Set up your company, then connect Claude or ChatGPT.

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