# x402-toolbox ISBN Validator

> x402-toolbox ISBN Validator is a paid API for AI agents from x402-toolbox.shablony-pro.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-29).

Validates whether a given ISBN (International Standard Book Number) string is correctly formatted and legitimate

## Facts

- Endpoint: GET https://x402-toolbox.shablony-pro.workers.dev/validation/isbn-validator?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-toolbox-isbn-validator-4c5d6c78
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_W-caH_WM0KAAt0BBGD9M1

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 x402-toolbox-isbn-validator-4c5d6c78
```

Example prompt: Can you check whether '978-3-16-148410-0' is a valid ISBN number?

## When to prefer this

Choose this endpoint when you need a lightweight, no-signup, pay-per-call ISBN validation without managing API keys or accounts. Ideal for AI agents performing one-off or low-volume book identifier checks where the x402 micropayment model fits — especially in automated pipelines ingesting bibliographic data where ISBN integrity must be confirmed cheaply and programmatically.

## Known failure modes

- Invalid or missing schema/ISBN input returns an error or ok:false
- Malformed ISBN that fails checksum returns validation failure
- Payment failure via x402 protocol results in unpaid/unauthorized response
- Ambiguous input format (missing hyphens, wrong length) may yield false negatives

## How this service works

309 deterministic pay-per-call tools for AI agents over x402 (USDC, Base). No signup, no API key: the payment is the identity.

## Output

Returns a JSON object with an 'ok' boolean indicating whether the endpoint call succeeded and a 'paid' boolean confirming the x402 micropayment was processed, along with the ISBN validation result indicating whether the provided ISBN is correctly formatted and passes checksum verification.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "schema": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "paid": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-toolbox-isbn-validator-4c5d6c78/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-toolbox.shablony-pro.workers.dev](https://www.zero.xyz/host/x402-toolbox.shablony-pro.workers.dev/llms.txt)