# Delx Commerce ISBN Check API

> Delx Commerce ISBN Check API is a paid API for AI agents from commerce.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).

Validates and looks up book metadata by ISBN number, returning bibliographic information for a given book identifier

## Facts

- Endpoint: POST https://commerce.delx.ai/api/v1/x402/isbn-check?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-commerce-isbn-check-api-7db33a92
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-jG941WUJfTPTe-9Es018

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 delx-commerce-isbn-check-api-7db33a92 -d '<json body>'
```

Example prompt: Can you check whether ISBN 978-0-06-112008-4 is valid and tell me what book it belongs to?

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-call ISBN validation and metadata lookup with no signup or subscription — ideal for agents processing individual book identifiers on-demand, enriching product catalogs, or verifying book data before purchase or listing, especially when USDC micropayment billing via x402 is already integrated.

## Known failure modes

- Invalid or malformed ISBN format returns an error or invalid flag
- ISBN not found in database returns empty or not-found response
- Network timeout on upstream bibliographic data source
- Malformed request body missing required fields returns 400-level error
- ISBN checksum fails validation

## How this service works

Pay-per-result APIs for agents. No signup. Exact price. Verifiable delivery. USDC on Base + Solana via x402.

## Output

A JSON object containing ISBN validity status and associated bibliographic metadata such as title, author, publisher, edition, and other book details if the ISBN resolves to a known record.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input",
  "output"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "additionalProperties": true
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type",
    "example"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "json"
    },
    "example": {
     "type": "object",
     "additionalProperties": true
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {}
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-commerce-isbn-check-api-7db33a92/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from commerce.delx.ai](https://www.zero.xyz/host/commerce.delx.ai/llms.txt)