# Duo Data Utilities – National ID / Tax / Company Number Validator

> Duo Data Utilities – National ID / Tax / Company Number Validator is a paid API for AI agents from api.duoleads.com, paid per call via x402, $0.05/call, status unknown (last checked 2026-10-02).

Validates a national identity, tax, or company registration number against its country's official checksum algorithm — structure and check-digit only, no registry lookup or personal data stored.

## Facts

- Endpoint: GET https://api.duoleads.com/v1/id/national?utm_source=zero.xyz
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/duo-data-utilities-national-id-tax-company-number-validator-5987daac
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_0fBHH0XCMoUxfQEAwLtvQ

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability duo-data-utilities-national-id-tax-company-number-validator-5987daac
```

Example prompt: Can you check whether the Dutch BSN number '111222333' is structurally valid — just the checksum, no registry lookup?

## When to prefer this

Choose this endpoint when you need a fast, deterministic, offline-style checksum validation of a national ID or tax number — it covers 23 countries and explicitly makes no registry call, stores no personal data, and returns a normalised and formatted form alongside the validity result. Prefer it over full KYC or registry-lookup services when you only need structural correctness (e.g. for form validation, deduplication, or pre-screening before an expensive registry call).

## Known failure modes

- Unsupported country code returns an error indicating the country is not in the 23 supported list
- Unknown `kind` for a given country returns a validation error
- Malformed or empty `value` field returns a structural error before checksum evaluation
- Network or gateway errors return HTTP 4xx/5xx with no validation result
- Payment failure (x402) blocks the request before any computation

## How this service works

Validate a national identity, tax or company registration number against its country's official checksum rule. Covers 23 countries including NL BSN, ES NIF/NIE/CIF, IT codice fiscale, FR SIREN/SIRET, DE Steuer-ID, BE/PL/CZ national numbers, SE/NO/DK/FI personal numbers, BR CPF/CNPJ, AU ABN/TFN, UK NINo, IE PPS, US NPI/EIN. Structure and check digit only — no registry lookup; the number itself is never stored (logs keep only its length and character types).

## Output

Returns a JSON object with a `valid` boolean, optional `reason` string explaining any failure, the `normalised` (stripped) form, the `formatted` canonical form, the `algorithm` name used (e.g. elfproef-11), any `derived` fields extracted from the number, plus standard `meta` including request ID, timestamp, price, and deterministic flag.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "country",
      "kind",
      "value"
     ],
     "properties": {
      "kind": {
       "type": "string",
       "maxLength": 32,
       "description": "Identifier type for that country, e.g. bsn, nif, cf, cpf."
      },
      "value": {
       "type": "string",
       "maxLength": 64,
       "description": "The identifier. Separators (space . - /) are stripped before checking."
      },
      "country": {
       "type": "string",
       "maxLength": 16,
       "description": "ISO 3166-1 alpha-2 country code, case-insensitive. One of the 23 supported countries; the United Kingdom is accepted as UK or GB (the response echoes what you sent)."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "ok",
      "route",
      "version",
      "data",
      "meta"
     ],
     "properties": {
      "ok": {
       "const": true
      },
      "data": {
       "type": "object",
       "required": [
        "valid",
        "country",
        "kind",
        "algorithm",
        "normalised",
        "formatted",
        "reason",
        "derived"
       ],
       "properties": {
        "kind": {
         "type": "string"
        },
        "valid": {
         "type": "boolean"
        },
        "reason": {
         "type": [
          "string",
          "null"
         ]
        },
        "country": {
         "type": "string"
        },
        "derived": {
         "type": "object",
         "properties": {
          "sex": {
           "type": "string"
          },
          "birth_date": {
           "type": "string"
          },
          "birth_month": {
           "type": [
            "number",
            "null"
           ]
          },
          "birth_year_yy": {
           "type": "string"
          },
          "birthplace_code": {
           "type": "string"
          },
          "century_assumed": {
    
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "data": {
   "kind": "bsn",
   "valid": true,
   "reason": null,
   "country": "NL",
   "derived": {},
   "algorithm": "elfproef-11",
   "formatted": "111.222.333",
   "normalised": "111222333"
  },
  "meta": {
   "price_usd": "0.05",
   "disclaimer": "Factual output of a deterministic computation over public data. Provided as is, with no warranty of accuracy, completeness or availability. Not investment, financial, legal, tax, medical or any other professional advice, and not a recommendation. Verify before relying on it. Terms: https://api.duoleads.com/terms",
   "request_id": "01K6B7Q4ZC8H3F2M9WXR5TYN0D",
   "computed_at": "2026-09-28T12:00:00.000Z",
   "deterministic": true
  },
  "route": "/v1/id/national",
  "version": "1.0.0"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/duo-data-utilities-national-id-tax-company-number-validator-5987daac/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.duoleads.com](https://www.zero.xyz/host/api.duoleads.com/llms.txt)