# GS1 Barcode Check Digit Calculator and Verifier

> GS1 Barcode Check Digit Calculator and Verifier is a paid API for AI agents from barcode-qr.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-11-02).

Computes or verifies the GS1 mod-10 check digit for EAN-8, UPC-A, EAN-13, ITF-14 (GTIN-14), and SSCC barcode numbers.

## Facts

- Endpoint: GET https://barcode-qr.x402tookit.com/barcode-check-digit?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/gs1-barcode-check-digit-calculator-and-verifier-82705fce
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_GWTX54THo5DTIuy2CWCyu

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 gs1-barcode-check-digit-calculator-and-verifier-82705fce
```

Example prompt: Can you verify whether the EAN-13 barcode 4006381333931 has the correct check digit, or compute what it should be?

## When to prefer this

Use this endpoint when you need to programmatically compute or validate GS1 mod-10 check digits for retail and logistics barcodes (EAN-8, UPC-A, EAN-13, ITF-14/GTIN-14, SSCC) without implementing the algorithm yourself. Prefer this over manual calculation or general-purpose math endpoints when GS1 standard compliance and type-specific validation are required.

## Known failure modes

- Invalid or non-numeric characters in the code
- Code length doesn't match the specified barcode type
- Unrecognized barcode type string
- Ambiguous length when type is not specified and auto-detection fails
- Network or payment authorization failure

## How this service works

Compute or verify the GS1 mod-10 check digit for EAN-8, UPC-A, EAN-13, ITF-14 (GTIN-14) and SSCC numbers.

## Output

Returns the computed check digit, the full barcode number including the check digit, the detected or specified barcode type, a verdict on whether a supplied check digit is correct, and the given check digit if one was provided. Also includes a summary and any reasons for failure.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "code"
     ],
     "properties": {
      "code": {
       "type": "string",
       "description": "Digits with or without the check digit, e.g. 4006381333931 or 400638133393"
      },
      "type": {
       "type": "string",
       "description": "ean8, upca, ean13, itf14 or sscc (default: guessed from the length)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "name": {
       "type": [
        "null",
        "string"
       ]
      },
      "type": {
       "type": [
        "null",
        "string"
       ]
      },
      "action": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "payload": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "checkDigit": {
       "type": [
        "null",
        "number"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "fullNumber": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "givenCheckDigit": {
       "type": [
        "null",
        "number"
       ]
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/gs1-barcode-check-digit-calculator-and-verifier-82705fce/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from barcode-qr.x402tookit.com](https://www.zero.xyz/host/barcode-qr.x402tookit.com/llms.txt)