Why manual gtin & barcode validator fails on real files

A barcode column that lost its leading zeros still looks like a number. It passes a spreadsheet review and fails at the marketplace, three days after upload.

You see this most often in product feeds, barcode imports, inventory reconciliations. Excel treats 0012345678905 as a decimal and stores 12345678905 — the zeros vanish before you ever see them.

What actually goes wrong

Manual handling fails in a specific way: it does not produce obviously broken output, it produces output that is almost right. Excel treats 0012345678905 as a decimal and stores 12345678905 — the zeros vanish before you ever see them. The mistake survives review because nothing looks wrong until an importer rejects the file or a report is quietly incorrect.

A cheaper habit

Check the file before it leaves your machine. That is the entire purpose of GTIN & Barcode Validator — it reads the data you paste, applies the same rules an importer would, and shows the row that will break, rather than a summary of how many rows broke.

The suggested padded value is what usually should have been in the column, which is more useful than a bare "invalid".

For the full picture — imports, feeds, variants, identifiers — see the pillar guide: Shopify product data management.

Try it on your own file

Open GTIN & Barcode Validator and paste a sample. It is free, it does not store anything, and you do not need an account. If the file is sensitive, save the page locally and run it offline.

Questions people ask

Which lengths are valid?

GTIN-8, 12, 13 and 14. Anything else is flagged with the padded value you probably meant.

Does it check the check digit?

Yes, the GS1 check digit is recomputed for every value.