# Are your barcodes valid GTINs?

> Validate up to 500 GTIN, UPC, EAN and ISBN-13 barcodes for free. Check digits, lengths and common errors before using product identifiers in Shopify.

Free gtin checker by catalogaudit: https://catalogaudit.app/gtin-checker (no signup, nothing stored beyond a salted IP hash used for daily limits).

## What it checks

- Validates GTIN-8, GTIN-12 (UPC), GTIN-13 (EAN, ISBN) and GTIN-14 codes, up to 500 at once
- Finds wrong check digits and shows the correct one
- Flags wrong lengths and restores leading zeros a spreadsheet dropped
- Flags restricted ranges Google rejects: in-store, variable-measure and coupon prefixes
- Shows the code type and the country of its GS1 prefix
- Validates the number only: doesn't look up the product or verify GS1 registration

## Questions

### What makes a GTIN valid for Google Merchant Center?

It has 8, 12, 13 or 14 digits, its last digit is the correct check digit for the rest, and its prefix isn't one of the restricted ranges: 02, 04 and 2x (in-store or variable-measure items) or coupon prefixes (05, 98, 99). Google disapproves items whose GTIN fails these checks.

### Why did my UPC lose its leading zero?

Spreadsheets treat a barcode as a number and drop leading zeros, so a 12-digit UPC starting with 0 turns into 11 digits. Format the barcode column as text before pasting. The tool shows the code with the zero restored when that makes it valid.

### What if my product has no GTIN?

Leave the barcode field empty, and in your feed set identifier_exists to no. Don't put your SKU in the barcode field: an invalid GTIN is worse than none, because Google disapproves the item instead of treating it as a custom product.

## Next

- Run the free full audit, which includes these checks and more: https://catalogaudit.app/#audit
- More free tools: https://catalogaudit.app/tools
- Talk to us: hello@catalogaudit.app