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May 6, 2026

# GTIN / EAN / UPC Validator: Common Mistakes and Best Practices

Most problems with gTIN / EAN / UPC Validator aren't caused by not knowing what to do — they're caused by small, easy-to-miss mistakes that compound quietly over time. Here are the ones that come up most often.

Mistake 1: Copying a similar product's GTIN as a placeholder 'to fix later' — this immediately creates a false association between two unrelated listings.

Mistake 2: Ignoring check-digit validation and only checking that a code is the right length, letting typos through undetected.

Mistake 3: Not flagging genuinely GTIN-exempt products correctly, causing repeated feed rejections for items that were never going to have one.

The fix for most of these isn't more effort, it's a regular check. A few habits that prevent them from creeping back in:
- 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.
- Re-verify GTINs after any product data migration — imports from spreadsheets are a common source of transposed or truncated digits.

Worth reading alongside this: our guide to product feed validation, which covers the adjacent side of the same part of a technical SEO audit.

GTIN / EAN / UPC Validator catches most of this automatically, which is the easiest way to stop these mistakes from shipping in the first place.

Try GTIN / EAN / UPC Validator yourself

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

Open GTIN / EAN / UPC Validator →
More on GTIN validation
GTIN / EAN / UPC Validator vs. Doing It by Hand: Is It Worth Switching?
A practical look at what GTIN / EAN / UPC Validator actually saves you over doing GTIN validation manually, and when manual still makes sense.
GTIN Validation FAQ: Questions People Actually Ask
Straight answers to the questions that come up most often about GTIN validation.
The GTIN Validation Checklist: What to Verify Before You Publish
A short, practical checklist for GTIN validation — the things worth checking every time, not just the first time.
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