# Agent402 UK GTIN Check Digit Validator

> Agent402 UK GTIN Check Digit Validator is a paid API for AI agents from agent402.co.uk, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Validates the GS1 check digit for GTIN-8, GTIN-12 (UPC), GTIN-13 (EAN), and GTIN-14 barcodes — checksum verification only, no product registry lookup.

## Facts

- Endpoint: POST https://agent402.co.uk/v1/validate/gtin
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent402-uk-gtin-check-digit-validator-ee37ae29
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ORHIQJeQ1BoIyYqnoaBUV

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 agent402-uk-gtin-check-digit-validator-ee37ae29 -d '<json body>'
```

Example prompt: Can you check if the barcode 5901234123457 is a valid GTIN — just verify the check digit, I don't need a product lookup.

## When to prefer this

Use this endpoint when you need a fast, cheap ($0.001) checksum-only gate before ingesting barcodes into a product catalog or database — it does not perform a product registry lookup, so it is ideal for bulk validation pipelines where you only need to confirm the GS1 check digit is mathematically correct for GTIN-8, UPC (GTIN-12), EAN (GTIN-13), or GTIN-14 codes.

## Known failure modes

- Non-numeric input or wrong digit count returns invalid/error
- GTIN length outside 8, 12, 13, or 14 digits is rejected
- Check digit mismatch returns valid_checksum: false but still parses the kind
- Malformed JSON body or missing gtin field returns 4xx error
- Network or payment failure (402) if USDC payment not attached

## How this service works

Don't burn tokens on deterministic work. Go/no-go jobs first: payout preflight, text firewall (PII/secrets), budget check — then rails, calendars, finmath. x402 USDC on Base. UK + global. agent402.co.uk — not agent402.tools. $0.001–$0.002 USDC on Base. No API keys.

## Output

Returns a JSON object with: the GTIN kind (e.g. GTIN-13), its alias (e.g. EAN-13), a top-level valid boolean, the normalized 14-digit GTIN-14 representation, and a valid_checksum boolean confirming whether the GS1 check digit is mathematically correct.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "gtin": {
   "type": "string",
   "description": "GTIN-8/12/13/14, EAN, or UPC digits"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "kind": "GTIN-13",
  "alias": "EAN-13",
  "valid": true,
  "gtin14": "05901234123457",
  "valid_checksum": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent402-uk-gtin-check-digit-validator-ee37ae29/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.co.uk](https://www.zero.xyz/host/agent402.co.uk/llms.txt)