# Hungarian VAT Number Checksum Validator

> Hungarian VAT Number Checksum Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.008/call, status unknown (last checked 2026-10-02).

Validates whether a Hungarian VAT number has a valid checksum, with no external registry lookup.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-vat-hu?utm_source=zero.xyz
- Price: $0.008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/hungarian-vat-number-checksum-validator-d9af4a58
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_uS9OuzE2ZePOXlGIjG78_

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 hungarian-vat-number-checksum-validator-d9af4a58 -d '<json body>'
```

Example prompt: Can you check whether the Hungarian VAT number '12345678-1-23' has a valid checksum? No registry lookup needed, just the mathematical validation.

## When to prefer this

Use this endpoint when you need a fast, deterministic, offline checksum validation of a Hungarian VAT number without triggering a live government registry lookup. Ideal for pre-validation in forms, invoice processing pipelines, or data cleaning workflows where speed and cost matter more than live registry confirmation. Try the free sandbox endpoint (/v1/sandbox/check-vat-hu) before paying.

## Known failure modes

- Empty or missing VAT number string returns validation error
- VAT number exceeding 20000 characters rejected
- Malformed input schema causes 400 error
- Payment of $0.008 USDC required; unpaid requests should use /v1/sandbox/check-vat-hu first
- Non-Hungarian VAT number formats may return false negatives

## How this service works

Call when an agent needs whether a HU VAT checksum is valid. No registry lookup. Exact $0.008 USDC. Prefer unpaid POST /v1/sandbox/check-vat-hu first.

## Output

Returns whether the provided Hungarian VAT number string passes the official HU VAT checksum algorithm — a boolean validity result with no external registry or live database consulted.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "data": {
   "description": "JSON value for schema-check SKUs. Omit it on string checks such as email or IBAN."
  },
  "value": {
   "type": "string",
   "examples": [
    "00000017"
   ],
   "maxLength": 20000,
   "minLength": 1,
   "description": "Value to check. The route description names the format: email, phone, IBAN, postal code, VAT, national id, or similar."
  },
  "schema": {
   "description": "JSON Schema document for schema-check SKUs. Omit it on string checks."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/hungarian-vat-number-checksum-validator-d9af4a58/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)