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Polish NIP Format & Checksum Validator (x402)
x402
Polish NIP Format & Checksum Validator (x402) is a paid API for AI agents from validate.crewofthecaptain.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-12).
Validates the format and checksum of a Polish NIP (tax identification number) via a pay-per-call API using x402 micropayments.
Price / call$0.001
Success—
StatusUnknown
How this service works
Format and checksum validation for IBAN, EU VAT, Polish NIP/REGON/PESEL and email, pay-per-call via x402. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base.
Output
Returns a JSON object with: 'type' (pl-nip), 'valid' (boolean indicating whether the NIP passes format and checksum rules), 'reason' (a string explaining the result or error, e.g. 'ok' or a specific failure reason), and 'normalized' (the canonical normalized form of the NIP number).
Example use cases
Supplier onboarding NIP verification
“Before I add this Polish company to our vendor list, can you verify their NIP number 5260001483 is valid and properly formatted?”
Invoice validation before payment
“I have an invoice from a Polish contractor with NIP 1234563218 — can you check if that NIP is legitimate and passes checksum so I can approve payment?”
Batch data cleanup for CRM
“I've got a Polish NIP '123-456-32-18' that a customer entered on our form — can you validate it and give me the normalized version we should store in our CRM?”
Technical details
Endpoint
POSThttps://validate.crewofthecaptain.com/api/validate/pl-nip?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you specifically need to validate Polish NIP (tax identification) numbers with checksum verification, particularly in workflows involving Polish business partners, invoicing, supplier onboarding, or CRM data cleanup. It is ideal for pay-per-call usage at $0.001/call without subscription overhead. Use sibling endpoints on the same service for IBAN, EU VAT, REGON, PESEL, or email validation.
Side effects
- Invalid or malformed NIP string returns valid:false with a reason describing the format or checksum failure
- Empty or missing 'value' field may return a validation error
- Non-string or overlong input (>512 chars) rejected by schema
- Payment failure via x402 results in HTTP 402 before validation occurs
- Network timeout or service unavailability returns HTTP 5xx
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| value | string |
Output
Schema · Response
{
"type": "json",
"example": {
"type": "pl-nip",
"valid": true,
"reason": "ok",
"normalized": "…"
}
}Tags
x402
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