# ISBN Validation API

> ISBN Validation API is a paid API for AI agents from api.aventtech.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Validates ISBN-10 or ISBN-13 numbers, returning whether the identifier is valid and its kind

## Facts

- Endpoint: GET https://api.aventtech.com/validate/isbn
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/isbn-validation-api-2bdbe84d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jgbuUOS2wK6gYLqggyFvO

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability isbn-validation-api-2bdbe84d
```

Example prompt: Can you check whether the ISBN 978-3-16-148410-0 is valid and tell me if it's an ISBN-10 or ISBN-13?

## When to prefer this

Use this endpoint when you need to validate a book ISBN (ISBN-10 or ISBN-13) including check-digit verification, and need to identify which ISBN format is used. Prefer this over generic barcode validators (e.g. GTIN/EAN) when the identifier is specifically a book ISBN and format classification is needed.

## Known failure modes

- Missing 'isbn' query parameter returns error
- Non-ISBN string (letters, wrong length) returns valid:false
- Network timeout or server error returns HTTP 5xx
- Malformed request schema returns HTTP 400

## How this service works

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## Output

A JSON object with 'kind' (e.g. 'ISBN-13' or 'ISBN-10') and 'valid' (boolean) indicating whether the provided ISBN passes structural and check-digit validation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "isbn"
     ],
     "properties": {
      "isbn": {
       "type": "string",
       "description": "ISBN-10 or ISBN-13, hyphens/spaces allowed"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "kind": "ISBN-13",
  "valid": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/isbn-validation-api-2bdbe84d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.aventtech.com](https://www.zero.xyz/host/api.aventtech.com/llms.txt)