# Finnish VAT Number Checksum Validator

> Finnish VAT Number Checksum Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-02).

Validates the checksum of a Finnish (FI) VAT number without performing a live registry lookup

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-vat-fi?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/finnish-vat-number-checksum-validator-cc669aff
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__1XDI7Sr8qt54AxTwDzZg

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 finnish-vat-number-checksum-validator-cc669aff -d '<json body>'
```

Example prompt: Can you check whether the Finnish VAT number FI28493382 has a valid checksum — no need to look it up in any registry, just verify the number itself is correctly formed?

## When to prefer this

Use this endpoint when you need a fast, offline checksum verification of a Finnish VAT number and do not require confirmation that the business is actually registered with the Finnish Tax Administration. It is cheaper and faster than a live registry lookup. Try the free sandbox endpoint POST /v1/sandbox/check-vat-fi first before paying $0.004 USDC per call on this production endpoint.

## Known failure modes

- Empty or missing value field returns validation error
- Value exceeds 20,000 character limit
- Non-FI VAT format provided may return invalid or error
- Malformed request body returns 400-level error
- Payment failure or insufficient USDC balance blocks the request

## How this service works

Call when an agent needs whether a FI VAT checksum is valid. No registry lookup. Exact $0.004 USDC. Prefer unpaid POST /v1/sandbox/check-vat-fi first.

## Output

A response indicating whether the provided Finnish VAT number passes or fails the algorithmic checksum test, without querying any external tax authority registry

## 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": [
    "00000019"
   ],
   "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/finnish-vat-number-checksum-validator-cc669aff/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)