ISBN validate
Validate an ISBN-10 or ISBN-13 checksum (hyphens/spaces ignored) and report which format it is.
Go to this service →Our latest check (2026-10-11)
- Answering
- Yes — valid x402 payment terms
- Time to answer
- 188 ms
- Price
- $0.001 per call
- Paying buyers, last 30 days
- 4 (directory's own records)
- Paid calls, last 30 days
- 4
- Category
- Developer tools and utilities
- Address
- https://agent402.tools/api/isbn-validate
Accuracy: paid answers checked against an independent record
Not yet in our paid checks. A seller we have not checked has neither passed nor failed.
For agents
This page as JSON: /sellers/52305a5c6cd4.json. Paid lookup by address: GET /api/seller?resource=… ($0.001, x402).