# French VAT Number Checksum Validator

> French VAT Number Checksum Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.007/call, status unknown (last checked 2026-10-02).

Validates the checksum of a French VAT (TVA) number without performing a live registry lookup

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-vat-fr?utm_source=zero.xyz
- Price: $0.007/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/french-vat-number-checksum-validator-56ac4b60
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_RU1FudbxQzupF8poOndCn

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 french-vat-number-checksum-validator-56ac4b60 -d '<json body>'
```

Example prompt: Can you check whether the French VAT number FR83404833048 has a valid checksum — no need to look it up in any registry, just verify the format and checksum are correct?

## When to prefer this

Choose this endpoint when you need fast, offline checksum validation of a French VAT number without incurring the latency or cost of a live VIES or government registry lookup. It is ideal for pre-filtering invalid numbers before expensive registry calls, or when registry availability is unreliable. Use the free sandbox endpoint POST /v1/sandbox/check-vat-fr first during development. Do not use this if you need to confirm the VAT number is actually registered and active with French tax authorities — that requires a live registry lookup.

## Known failure modes

- Input string is empty or missing — returns validation error
- VAT number exceeds 20 character limit — rejected by schema
- Non-FR VAT number format submitted — may return invalid or error
- Network or payment failure (x402 USDC payment not processed) — request not fulfilled
- Malformed JSON body — returns 400-level error

## How this service works

Call when an agent needs whether a FR VAT checksum is valid. No registry lookup. Exact $0.007 USDC. Prefer unpaid POST /v1/sandbox/check-vat-fr first.

## Output

Returns whether the provided French VAT number passes the checksum algorithm — a boolean validity result based purely on the mathematical checksum, with no external registry or VIES lookup performed.

## 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": [
    "00000000093"
   ],
   "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/french-vat-number-checksum-validator-56ac4b60/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)