contix herramientas

Free no-auth tools for Spain: validate IBAN, EU VAT check (VIES), Modelo 303 sums, Verifactu dates.

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What it can do

    What data it sees

    Do you need an account

    No: the server works without sign-in

    Free no-auth tools for Spain: validate IBAN, EU VAT check (VIES), Modelo 303 sums, Veri*factu dates.

    How to connect

    How to connect contix herramientas to Claude

    The server address to paste into Claude settings:

    https://api.contix.es/api/v1/mcp/herramientas

    1. Open Claude (claude.ai or the desktop app).
    2. Go to Settings → Connectors.
    3. Click Add custom connector.
    4. Paste the server address copied below into Remote MCP server URL and click Add.
    5. In a chat, click + → Connectors and switch the new connector on.

    Custom connectors are available on Free, Pro, Max, Team and Enterprise plans (Free is limited to one). On Team and Enterprise an organization Owner adds the connector first under Organization settings → Connectors.

    Authorization

    After you click Add, a sign-in window for the service opens. Sign in with your own account and approve access. Claude never sees your password.

    How to connect contix herramientas to ChatGPT

    The server address to paste into ChatGPT settings:

    https://api.contix.es/api/v1/mcp/herramientas

    1. Open ChatGPT in a browser (chatgpt.com). A Plus, Pro, Business, Enterprise or Edu plan is required.
    2. Turn on developer mode once: Settings → Apps → Advanced settings → Developer mode.
    3. Open Settings → Connectors and click Create.
    4. Fill in the form: Name (anything), Description (one line about what the service does), MCP server URL (copy it below).
    5. Under Authentication choose OAuth if the service requires sign-in, otherwise None. Click Create.
    6. In a new chat open + → Apps/Connectors and enable the connector.

    OpenAI has renamed this section before (Connectors → Apps/Plugins). If the label differs, search settings for "developer mode". On Business/Enterprise workspaces an admin must allow custom connectors first.

    Authorization

    On first use ChatGPT opens the service's sign-in window. Sign in and approve access.

    How to connect contix herramientas to Cursor

    The server address to paste into Cursor settings:

    https://api.contix.es/api/v1/mcp/herramientas

    Fastest: click Open in Cursor below and confirm the prompt.

    Manually:

    1. In Cursor open Settings → Cursor Settings → MCP and click Add new global MCP server.
    2. Paste the JSON copied below into ~/.cursor/mcp.json (per project: .cursor/mcp.json in the repo root).
    3. Save the file. The server appears in the MCP list; authorize it there if asked.

    Authorization

    If the service needs sign-in, an authorize button appears next to the server in the MCP list.

    Server tool list (6)

    Raw names from tools/list. Only developers need these.

    calculate_vatCompute the taxable base, VAT (IVA) amount, optional recargo de equivalencia and optional IRPF withholding from an amount. By default `importe` is the taxable base (sin IVA). With incluye_iva=true, `importe` is the TOTAL with VAT already included and the base is derived backwards (quitar IVA / reverse VAT). It only applies the rates it is given: it does NOT decide which VAT or IRPF rate applies to a case.
    validate_spanish_tax_idTwo modes in one input. If `valor` is only 1-8 digits, computes the DNI check letter and returns the full 8-digit-plus-letter DNI (digits are left-padded with zeros). If `valor` is a full document, validates its check character: DNI (8 digits + letter), NIE (X/Y/Z + 7 digits + letter) or CIF (entity letter + 7 digits + check digit or letter, with the entity type per Orden EHA/451/2008). Tolerates spaces, dots, dashes and an ES prefix. Pure arithmetic: it does NOT confirm the document exists, is active or belongs to the person who gave it.
    validate_ibanCheck whether an IBAN is well formed: country length (SWIFT IBAN registry) and ISO 13616 check digits. For Spanish IBANs also the two account check digits (DC) and the bank (entidad) with its BIC from the Banco de España registry. A 20-digit Spanish account number (CCC) is converted to its IBAN. Pure arithmetic: it does NOT confirm that the account exists or who owns it.
    check_vat_numberLook up an EU VAT number in the European Commission's VIES registry. Returns what the registry says: whether the number exists and, where the member state publishes it, the name and address. It draws NO tax conclusion. VIES is often down; that is reported as disponible=false, which is NOT the same as an invalid number.
    calculate_modelo_303Add up the boxes (casillas) of the Spanish quarterly VAT return Modelo 303 with the formulas printed on the official AEAT form: 27, 45, 46, 64, 66, 87, 69 and 71. Input are the tax amounts (cuotas) per box, e.g. {"09": 17430, "29": 9870}. It only sums what it is given: it does not decide which rate or deduction applies and it is not a tax return.
    get_obligation_datesDeadlines from the published Spanish rules: Veri*factu (RD 1007/2023, dates of RD-ley 15/2025) and mandatory B2B e-invoicing (RD 238/2026, counted from the ministerial order, provisional while the order is a draft). Information about the rules, not advice.