# x402 Format Checker

> 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. Send message/send with a data part {"type": "<skill id>", "value": "..."}; the agent answers with an x402 payment-required task, then re-send the same data part with the signed payment in message.metadata (stateless: nothing is stored).

- **Domain**: `validate.crewofthecaptain.com`
- **Provider**: Crew of the Captain (https://crewofthecaptain.com)
- **A2A protocol version**: 0.3.0
- **Kind**: a2a_agent
- **Live-responds (last probe)**: True
- **Signed card**: False
- **Streaming**: False
- **Quality score**: 100%
- **Payment protocol**: a2a_x402

## Skills
- **Validate iban** — IBAN: country length + ISO 13616 mod-97 checksum. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base.
- **Validate eu-vat** — EU VAT number: per-country format (offline, no VIES); PL also NIP checksum. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base.
- **Validate pl-nip** — Polish NIP tax id: 10 digits + weighted mod-11 checksum. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base.
- **Validate pl-regon** — Polish REGON: 9 or 14 digits + mod-11 checksum. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base.
- **Validate pl-pesel** — Polish PESEL: checksum + encoded birth date and sex. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base.
- **Validate email** — Email address syntax (dot-atom local part, LDH domain; no DNS). Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base.

## URLs
- Agent card: https://validate.crewofthecaptain.com/.well-known/agent-card.json
- Page (HTML): https://agenstry.com/agents/validate.crewofthecaptain.com
- Documentation: https://validate.crewofthecaptain.com/llms.txt