# Visa Card Luhn Validator

> Visa Card Luhn Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.007/call, status unknown (last checked 2026-10-24).

Validates whether a credit card number passes the Luhn algorithm and matches the Visa card format

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-card-visa?utm_source=zero.xyz
- Price: $0.007/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-24
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/visa-card-luhn-validator-1d921ffe
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_V4CKj58frhRPXZ6tP3feR

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 visa-card-luhn-validator-1d921ffe -d '<json body>'
```

Example prompt: Can you check whether 4532015112830366 is a valid Visa card number — run the Luhn check and confirm it matches the Visa format?

## When to prefer this

Use this endpoint when you need a stateless, privacy-safe check that a card number both passes the Luhn checksum and conforms to Visa's card number structure. Prefer the free sandbox endpoint POST /v1/sandbox/check-card-visa for testing before using this paid endpoint. Choose this over generic Luhn-only checkers when Visa network identification is also required.

## Known failure modes

- Input card number is empty or exceeds 20000 characters — returns validation error
- Card number contains non-numeric characters that prevent Luhn calculation
- Service unavailable or payment not processed — 402 or 5xx response
- Malformed request body missing the value field

## How this service works

Call when an agent needs whether a number passes Luhn and matches visa. Nothing is stored. Exact $0.007 USDC. Prefer unpaid POST /v1/sandbox/check-card-visa first.

## Output

Returns whether the provided card number passes the Luhn algorithm checksum validation and whether it matches the Visa card number format (typically 16 digits starting with 4). No card data is retained 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/visa-card-luhn-validator-1d921ffe/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)