The GTIN Validation Checklist: What to Verify Before You Publish

Run through this before you consider GTIN validation actually done:

1. Always validate the check digit, not just the length — a 13-digit string can still be an invalid EAN if the checksum doesn't match.
2. Use the manufacturer's officially assigned GTIN, never a self-generated placeholder — reusing or inventing codes causes catalog conflicts you don't control.
3. For products genuinely without a GTIN (custom, handmade, or pre-GS1 items), use the `identifier_exists: false` flag rather than leaving the field blank or fabricating a number.
4. Re-verify GTINs after any product data migration — imports from spreadsheets are a common source of transposed or truncated digits.
5. Double-check this after any site migration or major redesign, not just at launch.

None of these individually take long. The value is in doing all of them, every time, instead of remembering most of them most of the time.

Pair this with the Pinterest Shopping feed checklist if you're doing a fuller pre-launch pass.

GTIN / EAN / UPC Validator runs through most of this automatically.

Everything in this guide runs directly in your browser — no signup, no install.