{"openapi":"3.1.0","info":{"title":"Identifier Validators","version":"1.0.0","description":"Check digits and structure for ISBN, UPC/EAN, VIN, ISSN, ORCID, ISIN, CUSIP, LEI and MAC addresses. One call, one computed answer, no accounts or API keys. Machine-payable over x402.","x-guidance":"Identifier Validators: Check digits and structure for ISBN, UPC/EAN, VIN, ISSN, ORCID, ISIN, CUSIP, LEI and MAC addresses. Identifier Validators checks that an identifier is well formed using its published check-digit rule: ISBN-10 and ISBN-13 (/isbn-check), UPC and EAN barcodes (/gtin-check), vehicle VINs with country and model-year hints (/vin-check), ISSN (/issn-check), ORCID (/orcid-check), securities ISIN (/isin-check) and CUSIP (/cusip-check), legal-entity LEI (/lei-check) and MAC addresses (/mac-parse). A pass means well formed, not issued. Each paid GET returns a computed verdict with the reasons, the source and what was NOT checked. A verdict of UNVERIFIED means a lookup failed: treat it as unknown. No account or key: pay per call in USDC over x402."},"servers":[{"url":"https://id-validators.x402tookit.com"}],"paths":{"/cusip-check":{"get":{"operationId":"cusip_check","summary":"Validate a 9-character CUSIP security identifier check digit and split issuer and issue codes.","description":"Validate a 9-character CUSIP security identifier check digit and split issuer and issue codes.","tags":["identifiers","cusip","securities"],"parameters":[{"name":"id","in":"query","required":true,"description":"The CUSIP","schema":{"type":"string"}}],"responses":{"200":{"description":"The answer.","content":{"application/json":{"schema":{"type":"object","properties":{"verdict":{"type":["null","string"]},"summary":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"normalised":{"type":["null","string"]},"issuer":{"type":["null","string"]},"issue":{"type":["null","string"]},"checkDigit":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"source":{"type":["null","string"]},"asOf":{"type":["null","string"]},"disclaimer":{"type":["null","string"]}}},"example":{"verdict":"VALID","summary":"CUSIP 037833100 has a correct check digit.","reasons":["Structure and check digit are correct; this does not prove it was issued."],"normalised":"037833100","issuer":"037833","issue":"10","checkDigit":"0","degraded":false,"notChecked":["whether the identifier was ever issued or assigned","who it belongs to"],"source":"computed locally","asOf":"2026-10-11T04:20:50.807Z","disclaimer":"Screening signal computed from the named public source. 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Verify at the source before acting."}}}},"400":{"description":"A parameter was missing or out of range."},"402":{"description":"Payment Required"},"502":{"description":"The upstream source failed or timed out."}},"x-payment-info":{"price":{"mode":"fixed","currency":"USD","amount":"0.0200"},"protocols":[{"x402":{"network":"eip155:8453","scheme":"exact","currency":"USDC","endpoint":"https://id-validators.x402tookit.com/isbn-check"}},{"x402":{"network":"solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","scheme":"exact","currency":"USDC","endpoint":"https://id-validators.x402tookit.com/isbn-check"}},{"x402":{"network":"eip155:137","scheme":"exact","currency":"USDC","endpoint":"https://id-validators.x402tookit.com/isbn-check"}},{"x402":{"network":"eip155:42161","scheme":"exact","currency":"USDC","endpoint":"https://id-validators.x402tookit.com/isbn-check"}}]}}},"/isin-check":{"get":{"operationId":"isin_check","summary":"Validate a securities ISIN check digit and split it into country code and national security number.","description":"Validate a securities ISIN check digit and split it into country code and national security number.","tags":["identifiers","isin","securities"],"parameters":[{"name":"id","in":"query","required":true,"description":"The ISIN","schema":{"type":"string"}}],"responses":{"200":{"description":"The answer.","content":{"application/json":{"schema":{"type":"object","properties":{"verdict":{"type":["null","string"]},"summary":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"normalised":{"type":["null","string"]},"countryCode":{"type":["null","string"]},"nsin":{"type":["null","string"]},"cusipIfUS":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"source":{"type":["null","string"]},"asOf":{"type":["null","string"]},"disclaimer":{"type":["null","string"]}}},"example":{"verdict":"VALID","summary":"ISIN US0378331005 has a correct check digit.","reasons":["Structure and check digit are correct; this does not prove it was issued."],"normalised":"US0378331005","countryCode":"US","nsin":"037833100","cusipIfUS":"037833100","degraded":false,"notChecked":["whether the identifier was ever issued or assigned","who it belongs to"],"source":"computed locally","asOf":"2026-10-11T04:20:51.585Z","disclaimer":"Screening signal computed from the named public source. 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