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VAT MOD97 Checksum Validator
x402
VAT MOD97 Checksum Validator is a paid API for AI agents from hcrb.in, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-12).
Validates VAT numbers using the MOD97 checksum algorithm, returning validity, reason, country, and normalized form — offline and deterministic, no ML or external lookups.
Price / call$0.005
Success—
StatusUnknown
How this service works
Offline deterministic checks (no ML, no scraping) for business identifiers and rental due-diligence, paid per call via x402 (gasless EIP-3009 USDC on Base). Checksum-verifiable (IBAN, LEI, VAT, ABA, ISBN, SEDOL…) vs format-only (EIN, IFSC, SWIFT/BIC…) — every response returns a scope field. Non-custodial, signed receipts. First 3 calls/day free.
Output
A JSON object with a 'valid' boolean, a 'reason' string explaining the result (e.g. 'checksum valid' or 'invalid checksum'), the detected 'country', the 'normalized' VAT number string, a 'scope' field indicating whether this was a checksum-verifiable or format-only check, and the 'tool' name used.
Example use cases
Supplier onboarding VAT verification
“Before we add this new German supplier to our system, can you verify their VAT number DE345678901 is legitimate using a checksum — not just format, but actual MOD97 validation?”
Invoice compliance check for EU business
“I'm about to send an invoice to a company with VAT number FR61954506077 — can you validate that number with a real checksum so I know it's correct before I submit?”
Bulk vendor due diligence pre-screening
“We have a vendor claiming VAT number GB123456789 — run a deterministic checksum validation on it and tell me if it's valid, what country it belongs to, and the normalized format.”
Technical details
Endpoint
POSThttps://hcrb.in/v1/tools/vat-mod97-check/call?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a fast, offline, deterministic VAT number checksum validation without hitting tax authority APIs or external databases. Ideal for pre-screening vendor or customer VAT IDs during onboarding, invoice generation, or compliance workflows where you want algorithmic certainty (MOD97) rather than a live registry lookup. The 'scope' field tells you whether the result is checksum-verified or format-only, which is critical for risk-aware pipelines. At $0.005/call with the first 3 calls/day free, it's cost-effective for high-volume automated checks.
Side effects
- Malformed or missing VAT number input returns valid=false with a reason explaining the format issue
- Unsupported country prefix returns a scope indicating format-only check or an error reason
- Network or payment failure (x402) prevents the call from completing
- Edge-case VAT numbers that pass checksum but are not actually registered — this endpoint does NOT verify registration with tax authorities
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| input | object |
Output
Schema · Response
{
"type": "json",
"schema": {
"type": "object",
"required": [
"valid",
"reason"
],
"properties": {
"tool": {
"type": "string"
},
"scope": {
"type": "string"
},
"valid": {
"type": "boolean"
},
"reason": {
"type": "string"
},
"country": {
"type": "string"
},
"normalized": {
"type": "string"
}
}
},
"example": {
"valid": true,
"reason": "checksum valid"
}
}Tags
x402
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