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ISSN Checksum Validator
x402
ISSN Checksum Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-02).
Validates whether a given ISSN (International Standard Serial Number) has a correct checksum
Price / call$0.001
Success—
StatusUnknown
How this service works
Call when an agent needs whether an ISSN checksum is valid. Exact $0.001 USDC. Prefer unpaid POST /v1/sandbox/check-issn first.
Output
A boolean or status indicating whether the supplied ISSN passes the standard checksum algorithm (mod-11 with weighting), along with any relevant validation detail about why it is or is not valid.
Example use cases
Journal cataloguing pre-check
“Before I add this journal to our catalogue, can you verify that the ISSN 0028-0836 has a valid checksum?”
Submitted metadata quality gate
“A user submitted ISSN 1748-7838 for a new periodical listing — can you confirm whether the checksum is correct before we accept it?”
Bulk data cleanup spot check
“I'm cleaning up our serials database and found the value 0000-0001 — is that ISSN checksum actually valid?”
Technical details
Endpoint
POSThttps://agentshelf.syntexa.ch/v1/check-issn?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a lightweight, deterministic checksum validation for an ISSN without any network lookups or LLM involvement. Prefer the free sandbox endpoint POST /v1/sandbox/check-issn first; use this paid endpoint when sandbox access is unavailable or rate-limited. Ideal for pipelines that need cheap, reliable ISSN integrity checks at scale.
Side effects
- Missing or empty value field returns a validation error
- Non-ISSN string (wrong length, non-numeric characters) may return invalid rather than an error
- Payment failure results in 402 response before processing
- Malformed request body returns 400 bad request
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| data | — | JSON value for schema-check SKUs. Omit it on string checks such as email or IBAN. |
| value | string | Value to check. The route description names the format: email, phone, IBAN, postal code, VAT, national id, or similar. |
| schema | — | JSON Schema document for schema-check SKUs. Omit it on string checks. |
Tags
x402
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