ISBN Validator API

About the ISBN Validator API

ISBN Validator works by analyzing ISBN-10 and ISBN-13 numbers, validating their checksum algorithms, and extracting information about the group, publisher, and title identifiers. A valid number is also converted between the two formats with a freshly computed check digit; 979-prefixed ISBN-13s have no ISBN-10 form. Handles both formats with or without separators.

What people use it for

Book Cataloging

Validate ISBNs when adding books to library catalogs or inventory management systems

E-commerce

Verify ISBN accuracy in book listings on e-commerce platforms to prevent listing errors

Publishing

Validate ISBNs during book registration and publishing workflows to ensure correct formatting

Data Quality

Check ISBN validity in book databases during data cleaning and migration projects

Ways to call it

One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.

JSON

Default REST response

XML

Markup format

YAML

Human-readable

CSV

Tabular export

Beta

GraphQL

Query language

New

MCP

For AI agents

Request parameters — GET /v1/isbnvalidator

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Required

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curl "https://api.apiverve.com/v1/isbnvalidator?isbn=978-0-306-40615-7" \
  -H "x-api-key: YOUR_API_KEY"

Authentication

Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.

Response — GET /v1/isbnvalidator

Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.

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{
  "status": "ok",
  "error": null,
  "data": {
    "valid": true,
    "isbn": "978-0-306-40615-7",
    "type": "ISBN-13",
    "normalized": "9780306406157",
    "formatted": "978-0-306-40615-7",
    "checksum_valid": true,
    "prefix": "978",
    "group": "0",
    "publisher": "306",
    "title": "40615",
    "check_digit": "7",
    "error": null,
    "isbn10": "0306406152",
    "isbn13": "9780306406157"
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Response headers

Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

What a call costs — 2 credits per call

Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.

Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.

Zero-code embed — one snippet, no backend

Drop an interactive ISBN Validator form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.

Changelog — ISBN Validator API

Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.

Currently v1