How it works
Brand owners license a company prefix from GS1 and assign a GTIN to each trade item, including each size or color. UPC-A codes are 12 digits and EAN-13 codes are 13, and both are forms of GTIN. Retailers and marketplaces use GTINs to identify products across sellers, which is why many require one before a listing goes live.
Example
A brand's gray eight-foot rug has GTIN 00812345678905. Amazon, Walmart and the brand's PIM all reference the same GTIN, even though each uses its own SKU.
In integrations
GTINs make cross-system matching reliable when SKUs differ. The Unify Catalog API is designed to carry GTIN as a core product field and to match items across PIMs, storefronts and ERP item masters by GTIN, SKU or a key you choose, with conflicts reported rather than guessed. Not every item has a GTIN: private-label goods, bundles and custom products often do not. Integrations need a fallback key and should never invent or reuse GTINs.