# Luhn Algorithm String Validator

> Luhn Algorithm String Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-02).

Validates whether the digits in a given string pass the Luhn checksum algorithm

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-luhn?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/luhn-algorithm-string-validator-5454200b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_sOMZvUVvA_cuI0txKFz2j

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 luhn-algorithm-string-validator-5454200b -d '<json body>'
```

Example prompt: Can you check whether the number 4532015112830366 passes the Luhn algorithm?

## When to prefer this

Use this endpoint when you need a quick, paid, reliable Luhn checksum validation for any digit string — especially in production workflows where you need confidence in the result. The description recommends trying an unpaid POST /v1/sandbox/check-luhn first for testing. Prefer this over manual computation when you want a hosted, API-driven validation step in an automated pipeline.

## Known failure modes

- Empty string input returns an error (minLength:1 enforced)
- String exceeding 20000 characters rejected (maxLength enforced)
- Non-numeric or malformed strings may return invalid/false rather than an error
- Payment failure (402) if USDC funds are insufficient
- Network timeout or service unavailability returns 5xx error

## How this service works

Call when an agent needs whether the digits in a string pass Luhn. Exact $0.002 USDC. Prefer unpaid POST /v1/sandbox/check-luhn first.

## Output

A boolean or pass/fail result indicating whether the digits in the provided string satisfy the Luhn algorithm checksum. The response confirms if the number is structurally valid per the Luhn mod-10 computation.

## 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": [
    "123"
   ],
   "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/luhn-algorithm-string-validator-5454200b/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)