Billy MCP server

Read Billy invoices, bills, contacts, products and postings; create contacts and draft invoices. Hosted by usefulapi: connect it to Claude, ChatGPT, Cursor or any MCP client.

Connect BillyFree 50 calls/mo

What can I ask?

Turn on the Billy connector, then ask in plain words. The AI picks the tools.

Which customer invoices are still unpaid and past their due date?
What did we invoice in total last month?
Show me all supplier bills from this quarter that are still waiting for approval.
Create a new customer called Acme Ltd with the email billing@acme-example.com.

What you can do with Billy in Claude and ChatGPT

For small businesses and accountants who do invoicing and bookkeeping in Billy.

Find unpaid invoices past their due date

The AI lists sales invoices by state and paid status with due date, amount and balance, and shows which customers owe money.

Total what you invoiced in a period

The AI lists sales invoices and credit notes for a date range or period, and sums the amount and tax.

Review supplier bills waiting for approval

The AI lists bills by state, supplier, dates or paid status and opens one bill with its lines.

Check bank lines and ledger postings

The AI lists the bank-statement lines of one bank account and the ledger postings for an account or period. It only reads; nothing is reconciled.

Add a customer and a draft invoice

The AI creates a contact, then a draft invoice for an existing contact. The draft is not sent; you approve it in Billy.

Changes data

How do I connect Billy?

Before you connect

The login page asks for your Billy access token.

Create a token in Billy (mit.billy.dk) under Settings → Access tokens → Create access token, then copy it with the magnifier icon. A token belongs to one company; connect once per company. Your token is used only to call the Billy API on your behalf and can be deleted in Billy at any time.

Claude claude.ai · Desktop

Open Customize → Connectors, then click + Add → Add custom connector.
Enter the name Billy and this URL, then click Add:
https://billy.usefulapi.io/mcp
Claude opens the login page: enter your Billy access token.
In a chat, click + → Connectors and turn on Billy.

Team and Enterprise: an Owner adds the connector for the organization first.

ChatGPT chatgpt.com

Open Plugins, click +, then Add custom MCP server.
Enter the name Billy and this URL, choose OAuth as the authentication, confirm the warning and create it:
https://billy.usefulapi.io/mcp
ChatGPT opens the login page: enter your Billy access token.
In Plugins, install Billy, then choose it in a chat.

No Add custom MCP server option? It depends on your account or workspace settings: see OpenAI's guide.

Claude Code

Run this command, then run /mcp in Claude Code to log in:

claude mcp add --transport http billy https://billy.usefulapi.io/mcp

Cursor

Add to Cursor or add this to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "billy": {
      "url": "https://billy.usefulapi.io/mcp"
    }
  }
}

VS Code

Add to VS Code or add this to .vscode/mcp.json:

{
  "servers": {
    "billy": {
      "type": "http",
      "url": "https://billy.usefulapi.io/mcp"
    }
  }
}

Codex

Run these commands. The second one opens the login page:

codex mcp add billy --url https://billy.usefulapi.io/mcp

codex mcp login billy

Other clients

Windsurf, Cline, Zed and other MCP clients: add this URL as a remote MCP server (Streamable HTTP). The client then opens the login page in your browser.

https://billy.usefulapi.io/mcp

Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Billy access token. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.

Pricing

Plan	Price	Limit
Free	$0	50 tool calls / month
Proper user	$9/mo · $90/yr	10,000 tool calls / month
Pro+per user	$39/mo · $390/yr	100,000 tool calls / month

Each paid plan covers this Billy server only. Ask your AI to run billy_upgrade and choose Pro or Pro+, billed monthly or yearly (it returns a Stripe Checkout link). If you already have Pro, ask to change it to Pro+. The change requires your confirmation, keeps your billing interval and charges the price difference for the rest of the period immediately. Cancel any time with billy_cancel_subscription: your paid plan continues to the end of the paid period, with no refund for the current period, and asking to resume the same plan with billy_upgrade before then undoes the cancel. Or write to support@usefulapi.io.

Tools 19

Show all 19 tools (the AI picks them for you)

Read only · 13

Get the companybilly_get_organization
The Billy company the access token belongs to: id, name, address, registration (CVR) number, base currency, VAT settings, fiscal year, default payment terms, invoice numbering, default accounts. Good first call.
List contactsbilly_list_contacts
List customers and suppliers: name, type, address, CVR/registration number, EAN, payment terms, customer/supplier flags. The API has no documented search filter, so `search` is applied to the returned page only (case-insensitive on name, contact number and registration number); page on with next_page to look further. Paged.
Get a contactbilly_get_contact
One contact by id, with its contact persons (names and e-mail addresses).
List invoicesbilly_list_invoices
List sales invoices and credit notes (newest first by default): number, date, due date, state (draft/approved/voided), amount, tax, balance, isPaid, contactId, currency. Filter by state, customer, number, date, period, paid status or free text. Paged.
Get an invoicebilly_get_invoice
One invoice by id with its lines (product, description, quantity, unit price, amount, tax) and its payment associations.
List bills (supplier invoices)billy_list_bills
List bills (purchase invoices from suppliers): supplier, dates, state (draft/approved/voided), amount, balance, isPaid, supplier invoice number. Filter by state, supplier, dates or paid status. Paged.
Get a billbilly_get_bill
One supplier bill by id with its lines.
List productsbilly_list_products
List products and services usable as invoice lines: name, product number, description, sales account, archived flag. The API has no documented search filter, so `search` is applied to the returned page only (name, productNo). Paged.
Get a productbilly_get_product
One product by id with its unit prices per currency.
List accounts (chart of accounts)billy_list_accounts
The chart of accounts: account number, name, group, nature, VAT rate, bank-account flag and bank details (IBAN, bank name) of bank accounts. With is_bank_account=true this lists the bank accounts whose ids billy_list_bank_lines needs. Paged.
List tax (VAT) ratesbilly_list_tax_rates
The company's VAT rates: name, rate (as a fraction, 0.25 = 25 percent), whether it applies to sales or purchases, active flag. Paged.
List bank linesbilly_list_bank_lines
List the bank-statement lines of ONE bank account (read only; nothing is matched or reconciled): date, description, amount, side (debit/credit), reconciled flag, receipt state. Get the account id from billy_list_accounts with is_bank_account=true. Paged.
List ledger postingsbilly_list_postings
List ledger postings (the bookkeeping entries): date, text, account, amount, side (debit/credit), currency, voided flag. Filter by account, date or period. Read only. Paged.

Changes data · 2

Create a contactbilly_create_contact
WRITE: create ONE new contact (customer and/or supplier) in the company's Billy account. It does not check for duplicates (call billy_list_contacts first) and nothing is sent to the contact. Not idempotent: a repeat call creates a second contact.
Create a draft invoicebilly_create_draft_invoice
WRITE: create ONE invoice in the DRAFT state for an existing contact. The invoice is NOT approved, booked, numbered into the ledger or sent: the user reviews it in Billy and approves and sends it there. The invoice number is assigned by Billy. No payment is created. Not idempotent: a repeat call creates a second draft. POST /invoices with state=draft.

Your usefulapi plan · 4

Usage status (free-tier meter)billy_usage_status
Report the caller's current usage: the plan, calls used this month, the limit of the plan (the free monthly cap or the Pro fair use limit), remaining, and whether the limit is reached. Read-only; does not count against the meter.
Request a missing featurebilly_request_feature
Tell usefulapi that the user needs something the Billy tools cannot do yet (a missing tool, field or filter). Call it only when the user asks for something none of the tools can do, and tell the user that you send the request. Do not call it for errors or for normal requests. Do not include personal data, credentials or customer records. Stored with the product name and the client type (for example Claude or Cursor), without the user's account. At most 5 requests per day. Does not count against the meter.
Upgrade to Pro or Pro+billy_upgrade
Get a paid plan for Billy (the free tier caps monthly usage). Pro: 10,000 tool calls a month, for normal use — plan "monthly" ($9/month) or "yearly" ($90/year, 2 months free). Pro+: 100,000 tool calls a month, for automations and heavy use — plan "plus" ($39/month) or "plus_yearly" ($390/year). Without a plan it returns both Pro and Pro+, each with a payment link, for the user to choose; with a plan, one link. An existing Pro subscription changes to Pro+ in place: call without confirm first, as the reply states the exact charge for this account (the price difference for the rest of the period, or in a free Pro trial the full Pro+ price, as the trial ends); then call with confirm: true. Cancel any time: the plan then runs to the end of the paid period, so it also suits a one-time job. A link opens Stripe Checkout in the browser; after payment the account upgrades automatically. Does not count against the meter.
Cancel the Pro subscriptionbilly_cancel_subscription
Cancel the caller's Billy Pro subscription at the end of the paid period (no refund for the current period; Pro continues until then, then the free tier applies). Requires confirm: true. Run billy_upgrade later to undo the cancel before the period ends. Does not count against the meter.

FAQ

What can I do with Billy in Claude or ChatGPT?

Find unpaid invoices past their due date. Total what you invoiced in a period. Review supplier bills waiting for approval. Check bank lines and ledger postings. Add a customer and a draft invoice. See what you can do for the details.

Is this an official Billy product?

No. usefulapi is an independent service. It is not affiliated with or endorsed by Billy. The server calls the Billy API with your own Billy access, so it sees only the data that your account can see.

Can I connect Billy to Claude or ChatGPT?

Yes. In Claude, add this server's URL as a custom connector. In ChatGPT, add it as a custom MCP server in Plugins. Then log in once. Cursor, VS Code, Claude Code and Codex work too. See the setup steps.

What do I need to connect?

The login page asks for your Billy access token. See Before you connect for where to find it.

Do I put my Billy key or an Authorization header in the client config?

No. Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Billy access token. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.

How do you keep my Billy credentials?

The login stores them encrypted in the authorization grant of your connection. The server uses them to call the Billy API for you and to derive a private account id for usage metering. usefulapi does not show them on any page or in any reply. To stop all access, remove the connector and change or delete these credentials in Billy.

Can the AI change my Billy data?

Yes, if you approve it. 2 of the 15 Billy tools can create or change data. The other 13 are marked read-only. Most MCP clients ask you to approve a tool call before it runs.

What does it cost?

The Free plan gives 50 tool calls / month. Pro costs $9/mo or $90/yr, with 10,000 tool calls / month. Pro+ costs $39/mo or $390/yr, with 100,000 tool calls / month. Each subscription covers this Billy server only. Cancel any time: your paid plan then runs to the end of the paid period. Run billy_usage_status to see how many calls you used.

How do I subscribe or cancel?

Ask the AI to run billy_upgrade and choose Pro or Pro+, billed monthly or yearly: it returns a Stripe Checkout link. If you already have Pro, ask to change it to Pro+. After you confirm, your existing subscription changes in place, keeps its billing interval and charges the price difference for the rest of the period immediately. To cancel, run billy_cancel_subscription. Your paid plan continues to the end of the paid period.

What if a Billy tool that I need is missing?

Tell the AI what you wanted to do. It can send the request with billy_request_feature. We store the text with the server name, the type of AI client and the tool you tried, not with your account, and read every request when we plan new tools. You can send up to 5 requests per day.

Which AI clients can I use?

Any client that supports remote MCP servers (Streamable HTTP) with OAuth login: Claude (web and desktop), Claude Code, ChatGPT, Codex, Cursor, VS Code, Windsurf and others.

This is a Model Context Protocol endpoint — meant to be connected from an AI client, not opened in a browser. An invalid_token response at the URL is the auth gate working as designed; clients authenticate automatically.

Need a tool this server does not have, or a connection to another system? We build custom integrations and MCP servers.

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