Validate anything, per call. VAT · IBAN · email · place · VIN.
One unified validation suite for developers and agents — the utilities incumbents bill per call
(Vatstack $0.01–0.09) or bury in subscriptions. Check an EU VAT number live against VIES (with the registered
name & address); verify an IBAN's mod-97 checksum and pull its bank code; test an email for syntax,
a real MX record, disposable domains and role addresses; resolve a place to ISO 3166 codes from a bundled
dataset (no daily API limits); decode a VIN to make/model/year via NHTSA. Read-only, keyless, nothing stored —
emails are never kept and no mailbox is ever probed. Paid per call in USDC on Base via x402
or a prepaid credit key. Also a standalone MCP server.
Paid per call — $0.001 to $0.003.
Agents pay per call in USDC on Base via x402 (no account — an unpaid call returns a
signed 402 challenge to pay-and-retry). Humans can prepay by card and send an
X-FabTally-Key: fabt_… header instead. Bad input → 400, never charged.
Every validator has a rate-limited free teaser (this page uses them; paid adds the live VIES/MX/NHTSA lookups).
HTTP (x402) — POST any validator as JSON:
curl -XPOST https://valid.fabtally.com/v1/vat \
-d '{"country_code":"IE","vat_number":"6388047V"}'
→ 402 with a signed x402 challenge; pay in USDC on Base and retry with the X-PAYMENT header.
Prepaid credit — add X-FabTally-Key: fabt_… to charge a card-funded balance instead.
MCP server — streamable-http: https://valid.fabtally.com/mcp · also stdio (npm: fabtally-valid-mcp).
5 tools (validate_vat, validate_iban, validate_email, geo_lookup, decode_vin); paid tools relay the x402 challenge.
Discovery — /agent/overview · /openapi.json · /.well-known/x402