Billomat MCP server

Read Billomat clients, invoices, offers, credit notes, reminders; create clients and draft invoices. Hosted by usefulapi: connect it to Claude, ChatGPT, Cursor or any MCP client.

Connect Billomat50 free tool calls a month

What can I ask?

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

Which invoices are overdue right now and for which clients?
Give me total invoiced revenue per month for this year.
Which offers are still open and waiting for an answer?
Create a draft invoice for client Acme Ltd for 5 hours of consulting.

What you can do with Billomat in Claude and ChatGPT

For freelancers and small businesses that do invoicing and bookkeeping in Billomat.

Find overdue or open invoices and the clients behind them

The AI lists invoices filtered by client, status (DRAFT, OPEN, PAID, OVERDUE, CANCELED), dates or text. Each invoice has totals and the open amount, and you can also list payment reminders.

Total your invoiced revenue by month or client

The AI reads invoice totals grouped by client, status, day, week, month or year, with the same filters as the invoice list. You get revenue per month in one answer.

Check which offers are still open

The AI lists offers filtered by client, status (DRAFT, OPEN, WON, LOST, CANCELED, CLEARED), dates or text, and opens one for totals and validity.

Review supplier invoices you still have to pay

The AI lists incoming invoices from suppliers with status OPEN, PAID or OVERDUE and the open amount. It can open one and list suppliers.

Add a client, then prepare a draft invoice or offer

The AI creates a client, and a draft invoice or draft offer with line items. Drafts are not completed and not sent, so you review them in Billomat first.

Changes data

How do I connect Billomat?

Before you connect

The login page asks for your Billomat id and Billomat API key.

The Billomat id is the first part of your Billomat address (https://yourcompany.billomat.net). Create the key in Billomat → Einstellungen → Mitarbeiter → your user (enable API access, then generate the API key). The key acts with that user's rights; a dedicated user makes its activity easy to track. Your key is used only to call the Billomat API on your behalf; it is never shown to anyone.

Claude claude.ai · Desktop

Open Customize → Connectors, then click + Add → Add custom connector.
Enter the name Billomat and this URL, then click Add:
https://billomat.usefulapi.io/mcp
Claude opens the login page: enter your Billomat id and Billomat API key.
In a chat, click + → Connectors and turn on Billomat.

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 Billomat and this URL, choose OAuth as the authentication, confirm the warning and create it:
https://billomat.usefulapi.io/mcp
ChatGPT opens the login page: enter your Billomat id and Billomat API key.
In Plugins, install Billomat, 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 billomat https://billomat.usefulapi.io/mcp

Cursor

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

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

VS Code

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

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

Codex

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

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

codex mcp login billomat

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://billomat.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 Billomat id and Billomat API key. 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 account	$9/mo · $90/yr	10,000 tool calls / month
Pro+per account	$39/mo · $390/yr	100,000 tool calls / month

Each paid plan covers this Billomat server only. Ask your AI to run billomat_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 billomat_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 billomat_upgrade before then undoes the cancel. Or write to support@usefulapi.io.

Tools 38

Show all 38 tools (the AI picks them for you)

Read only · 28

Get the current userbillomat_get_current_user
Show the Billomat user the API key belongs to (name, email, role and rights). Use it to check which rights the key has.
Get the own company databillomat_get_company
Show the own company data of the Billomat account (name, address, bank details, tax numbers, currency).
List or search clientsbillomat_list_clients
List the clients (customers) of the account, filtered by name, number, email, contact person, country, note or tags. Paged.
Get a clientbillomat_get_client
Get one client with address, contact person, bank details, payment terms and revenue.
List articlesbillomat_list_articles
List the articles (products and services) with prices, units and tax. Paged.
Get an articlebillomat_get_article
Get one article with its prices, unit, tax and supplier.
List suppliersbillomat_list_suppliers
List the suppliers of the account, filtered by name, email, contact person, country, note or tags. Paged.
Get a supplierbillomat_get_supplier
Get one supplier with address and bank details.
List invoicesbillomat_list_invoices
List invoices (Rechnungen), filtered by client, status (DRAFT, OPEN, PAID, OVERDUE, CANCELED), number, date range, text or tags. Paged; each invoice carries totals and the open amount.
Invoice totals by groupbillomat_invoice_totals
Invoice totals grouped by client, status, day, week, month or year (for example group_by=client,year). Takes the same filters as billomat_list_invoices. Read-only.
Get an invoicebillomat_get_invoice
Get one invoice (status, totals, dates, client, payment terms). Its line items come from billomat_list_invoice_items.
List the items of an invoicebillomat_list_invoice_items
List the line items (positions) of one invoice.
List invoice paymentsbillomat_list_invoice_payments
List the payments that were recorded on invoices (read-only), optionally for one invoice, a date range or payment types.
List recurring invoicesbillomat_list_recurring_invoices
List recurring invoices (Abo-Rechnungen): name, cycle (DAILY, WEEKLY, MONTHLY, YEARLY), client and next run. Paged.
List offersbillomat_list_offers
List offers (Angebote), filtered by client, status (DRAFT, OPEN, WON, LOST, CANCELED, CLEARED), number, date range or text. Paged.
Get an offerbillomat_get_offer
Get one offer (status, totals, validity, client).
List order confirmationsbillomat_list_confirmations
List order confirmations (Auftragsbestaetigungen), filtered by client, status (DRAFT, COMPLETED, CANCELED, CLEARED), number, date range or text. Paged.
Get an order confirmationbillomat_get_confirmation
Get one order confirmation.
List delivery notesbillomat_list_delivery_notes
List delivery notes (Lieferscheine), filtered by client, status (DRAFT, CREATED), number, date range or text. Paged.
Get a delivery notebillomat_get_delivery_note
Get one delivery note.
List credit notesbillomat_list_credit_notes
List credit notes (Gutschriften), filtered by client, status (DRAFT, OPEN, PAID), date range or text. Paged.
Get a credit notebillomat_get_credit_note
Get one credit note.
List remindersbillomat_list_reminders
List payment reminders (Mahnungen), filtered by client, status (DRAFT, OPEN, OVERDUE, PAID, CANCELED), invoice number, date range or text. Paged.
Get a reminderbillomat_get_reminder
Get one payment reminder.
List incoming invoicesbillomat_list_incoming_invoices
List incoming invoices (Eingangsrechnungen, from suppliers), filtered by supplier, status (OPEN, PAID, OVERDUE), number, date range, note or tags. Paged.
Get an incoming invoicebillomat_get_incoming_invoice
Get one incoming invoice with amounts and open amount.
List tax ratesbillomat_list_taxes
List the tax rates (Steuersaetze) of the account, with the default one.
List unitsbillomat_list_units
List the units (Einheiten) used for article and item quantities, optionally filtered by name.

Changes data · 6

Create a clientbillomat_create_client
WRITE: create a new client (customer) in Billomat. Billomat assigns the client number. Nothing is sent to the client. Check billomat_list_clients first to avoid duplicates.
Update a clientbillomat_update_client
WRITE: change fields of an existing client (only the fields you pass are changed; everything else stays). Read the client first with billomat_get_client. Nothing is sent to the client.
Create an articlebillomat_create_article
WRITE: create a new article (product or service) with a price. Billomat assigns the article number.
Create a draft invoicebillomat_create_draft_invoice
WRITE: create an invoice as a DRAFT (Entwurf) for a client, with optional line items. The invoice is NOT completed, has no number yet and is NOT sent; review and complete it in Billomat. Nothing is charged.
Add an item to a draft invoicebillomat_add_invoice_item
WRITE: add one line item to an invoice that is still a DRAFT (Billomat refuses it for any other status). Does not complete or send the invoice.
Create a draft offerbillomat_create_draft_offer
WRITE: create an offer (Angebot) as a DRAFT for a client, with optional line items. The offer is NOT completed, has no number yet and is NOT sent; review and complete it in Billomat.

Your usefulapi plan · 4

Usage status (free-tier meter)billomat_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 featurebillomat_request_feature
Tell usefulapi that the user needs something the Billomat 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+billomat_upgrade
Get a paid plan for Billomat (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 subscriptionbillomat_cancel_subscription
Cancel the caller's Billomat 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 billomat_upgrade later to undo the cancel before the period ends. Does not count against the meter.

FAQ

What can I do with Billomat in Claude or ChatGPT?

Find overdue or open invoices and the clients behind them. Total your invoiced revenue by month or client. Check which offers are still open. Review supplier invoices you still have to pay. Add a client, then prepare a draft invoice or offer. See what you can do for the details.

Is this an official Billomat product?

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

Can I connect Billomat 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 Billomat id and Billomat API key. See Before you connect for where to find them.

Do I put my Billomat 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 Billomat id and Billomat API key. 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 Billomat credentials?

The login stores them encrypted in the authorization grant of your connection. The server uses them to call the Billomat 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 Billomat.

Can the AI change my Billomat data?

Yes, if you approve it. 6 of the 34 Billomat tools can create or change data. The other 28 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 Billomat server only. Cancel any time: your paid plan then runs to the end of the paid period. Run billomat_usage_status to see how many calls you used.

How do I subscribe or cancel?

Ask the AI to run billomat_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 billomat_cancel_subscription. Your paid plan continues to the end of the paid period.

What if a Billomat tool that I need is missing?

Tell the AI what you wanted to do. It can send the request with billomat_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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