Missing GTINs and identifiers

GTINs (barcodes — EAN, UPC, ISBN) are how channels identify products. Missing or invalid ones limit reach and cause disapprovals. Here's how to handle every case.

If you have the GTINs

Make sure the field is being read from your source and mapped to the feed's GTIN field. If they live in a Shopify metafield or a spare column, point a rule at that field.

If a GTIN is invalid

GTINs have a check digit, so a typo makes them invalid. Trajekt flags malformed identifiers; correct them at source or with a find & replace if there's a consistent error.

If a product genuinely has no GTIN

Custom-made, handmade or own-brand products may not have one. In that case, provide brand + MPN instead, and set the 'identifier exists' field to false so the channel knows not to expect a GTIN.

Bulk approach

For a catalogue with scattered gaps, combine rules: read GTINs where present, fall back to brand + MPN where not, and flag the rest. See the identifiers guide.