Számlázz.hu MCP server

Read Számlázz.hu invoices, PDFs, receipts, taxpayers; issue, reverse and pay invoices and receipts. Hosted by usefulapi: connect it to Claude, ChatGPT, Cursor or any MCP client.

Connect Számlázz.hu50 free tool calls a month

What can I ask?

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

Show me the details of invoice number E-2026-15, including the VAT breakdown.
Download the PDF of invoice number E-2026-15.
Check whether the Hungarian company with tax number 12345678 is a registered taxpayer.
Look up receipt number NYGTA-2026-8 and tell me if it was reversed.

What you can do with Számlázz.hu in Claude and ChatGPT

For Hungarian businesses and accountants who issue invoices and receipts with Számlázz.hu.

Read an invoice or download its PDF

Reads an issued invoice by invoice number, order number or external id, with lines, totals, VAT breakdown and payments, or downloads its PDF.

Check whether a Hungarian company is a registered taxpayer

Looks up the first 8 digits of a tax number in the NAV register and shows if it is valid, the taxpayer's name, VAT status and addresses.

Issue an invoice

Issues a real invoice in Számlázz.hu. A final invoice is reported to NAV and can only be cancelled by a reversal.

Changes data

Record payments on an invoice

Records 1 to 5 payments on an issued invoice or pro forma invoice, which updates its paid amount and outstanding balance.

Changes data

Reverse an invoice or delete a pro forma invoice

Issues a reversal (storno) invoice that cancels an issued invoice, or deletes a pro forma invoice. A real invoice cannot be deleted.

Changes data

Look up, issue, e-mail or reverse a receipt

Reads a receipt with its lines, payments and reversal status, issues a receipt, e-mails it to a customer, or reverses it.

Changes data

How do I connect Számlázz.hu?

Before you connect

The login page asks for your Számla Agent key.

Create the key in Számlázz.hu as the account owner or an administrator: Vezérlőpult (dashboard) → scroll down to Számla Agent kulcsok → click the key icon. The key has full rights on that account, never expires, and can be deleted there at any time. Számla Agent is a paid add-on of Számlázz.hu (billed monthly by the number of documents issued through the API); to try the tools without real documents, switch the account to test mode first. Your key is used only to call the Számlázz.hu 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 Számlázz.hu and this URL, then click Add:
https://szamlazz-hu.usefulapi.io/mcp
Claude opens the login page: enter your Számla Agent key.
In a chat, click + → Connectors and turn on Számlázz.hu.

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 Számlázz.hu and this URL, choose OAuth as the authentication, confirm the warning and create it:
https://szamlazz-hu.usefulapi.io/mcp
ChatGPT opens the login page: enter your Számla Agent key.
In Plugins, install Számlázz.hu, 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 szamlazz-hu https://szamlazz-hu.usefulapi.io/mcp

Cursor

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

{
  "mcpServers": {
    "szamlazz-hu": {
      "url": "https://szamlazz-hu.usefulapi.io/mcp"
    }
  }
}

VS Code

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

{
  "servers": {
    "szamlazz-hu": {
      "type": "http",
      "url": "https://szamlazz-hu.usefulapi.io/mcp"
    }
  }
}

Codex

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

codex mcp add szamlazz-hu --url https://szamlazz-hu.usefulapi.io/mcp

codex mcp login szamlazz-hu

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://szamlazz-hu.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 Számla Agent 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 Agent key	$9/mo · $90/yr	10,000 tool calls / month
Pro+per Agent key	$39/mo · $390/yr	100,000 tool calls / month

Each paid plan covers this Számlázz.hu server only. Ask your AI to run szamlazz_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 szamlazz_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 szamlazz_upgrade before then undoes the cancel. Or write to support@usefulapi.io.

Tools 15

Show all 15 tools (the AI picks them for you)

Read only · 4

Get an invoiceszamlazz_get_invoice
Read the data of one issued invoice (seller, buyer, lines, totals, VAT breakdown, payments) by invoice number, order number or your external id (give exactly one; for an order number with several invoices the last one is returned). Only invoices issued in this Számlázz.hu account. Also use it to check whether an invoice exists before issuing again. Számla Agent action-szamla_agent_xml.
Get the PDF of an invoiceszamlazz_get_invoice_pdf
Download the PDF of one issued document (invoice, pro forma, ...) by invoice number, order number or your external id (give exactly one). Returns the totals and the PDF as an embedded resource. Számla Agent action-szamla_agent_pdf.
Check a Hungarian taxpayerszamlazz_check_taxpayer
Look up a Hungarian taxpayer in the NAV register by the first 8 digits of the tax number (the törzsszám): whether the number is valid, the taxpayer's name, VAT status and addresses. Számla Agent action-szamla_agent_taxpayer (data from the NAV Online Invoice platform).
Get a receiptszamlazz_get_receipt
Read one issued receipt (nyugta) by receipt number: lines, payments, totals, whether it was reversed. Optionally the PDF. Számla Agent action-szamla_agent_nyugta_get.

Changes data · 7

Issue an invoice (fiscal, cannot be undone)szamlazz_create_invoice
ISSUES a real invoice in Számlázz.hu. A final invoice is reported to NAV (Online Számla) and can only be cancelled by a reversal (szamlazz_reverse_invoice), never deleted. kind: invoice (default), proforma (díjbekérő; not fiscal, can be deleted with szamlazz_delete_proforma), prepayment (előlegszámla). The tool computes net, VAT and gross of every line from net_unit_price and vat_rate. preview true builds the PDF only and creates NO document (check the reply: a returned invoice_number means a document WAS created). This call is NEVER retried: if the result is unclear, look the invoice up (szamlazz_get_invoice by order_number or external_id) before issuing again; always send external_id or order_number so that you can. Setting send_email_to_buyer e-mails the PDF to the buyer. Számla Agent action-xmlagentxmlfile.
Reverse (storno) an invoice (fiscal, cannot be undone)szamlazz_reverse_invoice
ISSUES a reversal (storno) invoice that cancels one issued invoice. Fiscal: it is reported to NAV and cannot be undone; the original stays in the books. A reversal needs the invoice number of a real invoice. NEVER retried: if the result is unclear, check with szamlazz_get_invoice before trying again. Számla Agent action-szamla_agent_st.
Delete a pro forma invoiceszamlazz_delete_proforma
DELETES one pro forma invoice (díjbekérő) by its number or by its order number (give exactly one). Only pro forma invoices can be deleted; a real invoice is never touched (use szamlazz_reverse_invoice). Cannot be undone. Számla Agent action-szamla_agent_dijbekero_torlese.
Register payments on an invoiceszamlazz_register_payment
Records 1-5 payments (kifizetés) on one of your own issued invoices or pro forma invoices, which updates its paid amount and outstanding balance. By default the payments are ADDED to the existing ones; replace_existing true REPLACES all earlier payment entries of the invoice. Not fiscal. Számla Agent action-szamla_agent_kifiz.
Issue a receipt (fiscal, cannot be undone)szamlazz_create_receipt
ISSUES a real HUF receipt (nyugta). Receipts are fiscal (NAV reporting) and can only be cancelled by szamlazz_reverse_receipt, never deleted. Give each line's whole-forint gross_total and vat_rate: the tool derives net, VAT and unit price (net + VAT equals gross exactly, as the vendor demands). The receipt prefix must be a receipt-only prefix (capital letters and digits, e.g. NYGTA), not an invoice prefix. call_id is required: the vendor refuses a second receipt with the same call_id (error 338), which protects against a duplicate. NEVER retried automatically: if the result is unclear, ask the user, then repeat the call with the SAME call_id (error 338 means the receipt already exists; find it in Számlázz.hu). Számla Agent action-szamla_agent_nyugta_create.
Reverse (storno) a receipt (fiscal, cannot be undone)szamlazz_reverse_receipt
ISSUES a reversal (storno) receipt that cancels one issued receipt. Fiscal and irreversible; a receipt can be reversed once, and a reversal receipt cannot be reversed. NEVER retried: if the result is unclear, check with szamlazz_get_receipt before trying again. Számla Agent action-szamla_agent_nyugta_storno.
E-mail a receiptszamlazz_send_receipt
E-MAILS an already issued receipt (PDF) to a customer. Without the e-mail fields, the vendor re-sends the receipt with the settings of the earlier e-mail. The e-mail cannot be recalled. Számla Agent action-szamla_agent_nyugta_send.

Your usefulapi plan · 4

Usage status (free-tier meter)szamlazz_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 featureszamlazz_request_feature
Tell usefulapi that the user needs something the Számlázz.hu 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+szamlazz_upgrade
Get a paid plan for Számlázz.hu (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 subscriptionszamlazz_cancel_subscription
Cancel the caller's Számlázz.hu 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 szamlazz_upgrade later to undo the cancel before the period ends. Does not count against the meter.

FAQ

What can I do with Számlázz.hu in Claude or ChatGPT?

Read an invoice or download its PDF. Check whether a Hungarian company is a registered taxpayer. Issue an invoice. Record payments on an invoice. Reverse an invoice or delete a pro forma invoice. Look up, issue, e-mail or reverse a receipt. See what you can do for the details.

Is this an official Számlázz.hu product?

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

Can I connect Számlázz.hu 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 Számla Agent key. See Before you connect for where to find it.

Do I put my Számlázz.hu 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 Számla Agent 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 Számlázz.hu credentials?

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

Can the AI change my Számlázz.hu data?

Yes, if you approve it. 7 of the 11 Számlázz.hu tools can create or change data. The other 4 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 Számlázz.hu server only. Cancel any time: your paid plan then runs to the end of the paid period. Run szamlazz_usage_status to see how many calls you used.

How do I subscribe or cancel?

Ask the AI to run szamlazz_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 szamlazz_cancel_subscription. Your paid plan continues to the end of the paid period.

What if a Számlázz.hu tool that I need is missing?

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