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Agent402 ISBN Check Digit Validator
x402
Agent402 ISBN Check Digit Validator is a paid API for AI agents from agent402.co.uk, paid per call via x402, $0.001/call, status down (last checked 2026-09-15).
Validates the check digit of an ISBN-10 or ISBN-13 number per ISO 2108, returning validity, kind, and bookland prefix status
Price / call$0.001
Success—
StatusDown
How this service works
Don't burn tokens on deterministic work. Go/no-go jobs first: payout preflight, text firewall (PII/secrets), budget check — then rails, calendars, finmath. x402 USDC on Base. UK + global. agent402.co.uk — not agent402.tools. $0.001–$0.002 USDC on Base. No API keys.
Output
Returns a JSON object indicating: 'kind' (ISBN-10 or ISBN-13), 'valid' (overall validity boolean), 'valid_checksum' (whether the check digit is correct per ISO 2108), and 'bookland_prefix' (whether the EAN bookland prefix is present, for ISBN-13).
Example use cases
Pre-ingest catalog ISBN check
“Before I add this book to the catalog, verify that the ISBN 0-306-40615-2 has a valid check digit so I don't store a corrupt entry.”
User-submitted ISBN form validation
“A user just typed in ISBN 9780140328721 on our order form — can you confirm the check digit is correct before we let them proceed to checkout?”
Bulk data cleanup flagging
“I have a record with ISBN 978-0-7432-7356-5 that might have a typo — can you validate the checksum and tell me if it's a proper ISBN-13?”
Technical details
Endpoint
POSThttps://agent402.co.uk/v1/validate/isbnWhen to prefer
Use this endpoint when you need a fast, cheap, authoritative ISO 2108 check-digit computation for ISBN-10 or ISBN-13 numbers — for example before catalog ingestion, form validation, or data cleaning. It is not a registry lookup (it won't tell you if the book exists or who published it), so prefer it purely for structural/checksum validation at $0.001 per call.
Side effects
- Malformed or non-ISBN string returns invalid result or error
- Passing a registry lookup query — this endpoint only checks structure/checksum, not whether the ISBN is registered
- Providing an empty string may return a validation error
- Non-string or missing 'isbn' field in request body causes a schema error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| isbn | string | ISBN-10 or ISBN-13 (hyphens ok) |
Output
Schema · Response
{
"type": "json",
"example": {
"kind": "ISBN-13",
"valid": true,
"valid_checksum": true,
"bookland_prefix": true
}
}Tags
x402
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