# Amex Card Number Validator (Luhn + Network Check)

> Amex Card Number Validator (Luhn + Network Check) is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.009/call, status unknown (last checked 2026-10-02).

Validates that a card number passes the Luhn algorithm and matches American Express card format, without storing any data.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-card-amex?utm_source=zero.xyz
- Price: $0.009/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/amex-card-number-validator-luhn-network-check-6c136072
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_w0Ip7A59DrjiM2nF9MFw8

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 amex-card-number-validator-luhn-network-check-6c136072 -d '<json body>'
```

Example prompt: Can you check if the card number 378282246310005 is a valid American Express card — run the Luhn check and confirm it matches the Amex format?

## When to prefer this

Use this endpoint when you specifically need to validate that a card number is both mathematically valid (Luhn) and belongs to the American Express network. Prefer the free sandbox POST /v1/sandbox/check-card-amex first for testing. Choose this over generic Luhn-only checkers when network identification (Amex specifically) is required alongside checksum validation.

## Known failure modes

- Missing or empty card number value returns validation error
- Non-numeric or malformed input may return format error
- Card number too long or too short may fail schema validation (maxLength 20000 chars)
- Network timeout or HTTP 402 if payment not handled correctly

## How this service works

Call when an agent needs whether a number passes Luhn and matches amex. Nothing is stored. Exact $0.009 USDC. Prefer unpaid POST /v1/sandbox/check-card-amex first.

## Output

Returns whether the submitted card number passes the Luhn checksum algorithm and whether it matches American Express card number patterns (starting digits and length). No data is persisted after the check.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "data": {
   "description": "JSON value for schema-check SKUs. Omit it on string checks such as email or IBAN."
  },
  "value": {
   "type": "string",
   "examples": [
    "411111"
   ],
   "maxLength": 20000,
   "minLength": 1,
   "description": "Value to check. The route description names the format: email, phone, IBAN, postal code, VAT, national id, or similar."
  },
  "schema": {
   "description": "JSON Schema document for schema-check SKUs. Omit it on string checks."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/amex-card-number-validator-luhn-network-check-6c136072/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)