Last updated: Sep 28, 2026 at 12:33PM
Nearly every marketplace Osello supports requires a barcode — a UPC, EAN, or other GTIN — on each variant before it can be submitted. Osello reads yours from the barcode field on each Shopify variant, so keeping barcodes clean in Shopify is the single best thing you can do for smooth submissions.
Why marketplaces insist on them
A GTIN (Global Trade Item Number) is the universal ID for a sellable item — UPC and EAN are the common 12- and 13-digit forms. Marketplaces use it to recognize your item, match it against products already in their catalog, and prevent duplicates. Without one, most marketplaces simply won't accept the variant, so Osello checks for a barcode before submitting.
On marketplaces that support it (Macy's, Nordstrom, Bloomingdale's, and other Mirakl-powered channels), Osello also uses the barcode — when a variant has one — as the product identifier on listing submissions and on price and inventory updates, so everything stays linked to the marketplace's product even if a variant's SKU changes later. Once a variant has been submitted, the barcode it was listed under stays fixed too — see Why a listing keeps its SKU, barcode, or style code.
Where Osello reads barcodes from
Each variant has one Barcode field, which holds whichever form of GTIN you use: UPC, EAN, JAN, ISBN or GTIN-14.
- Shopify fills it from the barcode field on each Shopify variant.
- Spreadsheet imports fill it from a Barcode, UPC, EAN, GTIN, JAN or ISBN column.
- You can type it in when you edit a product or variant in Osello.
Osello cleans values automatically — stripping dashes, stray spaces, and the trailing ".0" that spreadsheets sometimes add — and checks the format:
- A barcode is 8 to 14 digits, with no letters
- Every barcode must be unique across your catalog — two variants can't share one
- A SKU must be unique within its product — two variants of the same product can't share one
Values that fail these checks are rejected with an error explaining why.
Where to see them
- A product's page shows its Barcode right under the title (for single products).
- The Variants tab lists every variant with its SKU and barcode, so you can scan for gaps.
- Each variant's own page shows its SKU, barcode and MPN.
- A No barcode warning appears on a variant's page when it has none, and a No barcodes warning on a product's page when none of its variants has one. Marketplaces that require barcodes leave those variants out of Products to List until they get one.
How to fix a missing or wrong barcode
Best: fix it in Shopify. Enter the barcode on the variant in Shopify and it flows into Osello on the next sync — usually within about 15 minutes. Listing variants that don't have a barcode yet pick up the new value automatically.
If your barcodes can't live in Shopify, edit the product or variant in Osello and enter the barcode in its Barcode field. A Shopify sync only replaces it when the Shopify variant has a barcode of its own, so a barcode you enter in Osello stays put as long as the Shopify barcode is blank.
Already-listed variants keep their barcode. Once a listing variant has a barcode, the marketplace uses it to identify your product — and to keep price and inventory updates attached to it — so Osello won't swap it out just because the source value changed later. If a listed variant's barcode is genuinely wrong, remove the variant from the listing and add it back so it picks up the corrected barcode.