Most goods sold online have no GTIN, UPC or EAN because barcodes are issued per brand, and the majority of listings on marketplaces are unbranded goods produced by factories that never registered one. A barcode costs money and only pays for itself in retail distribution, which these products never enter. The consequence is that every price comparison engine, which matches products by identifier, is structurally blind to exactly the products with the widest price spreads.
What a GTIN actually is
A GTIN — the number behind a UPC or EAN barcode — is allocated to a company that registers with GS1 and pays for a prefix. It identifies a product from a specific brand.
A factory producing an unbranded phone tripod sold by forty different resellers has no reason to register one, and the resellers cannot share a single identifier because none of them owns the brand.
What breaks because of it
Comparison engines join listings on identifier first and title second. With no identifier, they fall back on titles — and marketplace titles are keyword-stuffed strings written to win a search, not to describe a product.
The result is that the goods with the biggest and most exploitable price differences are precisely the ones no comparison tool can line up side by side.
What can be matched instead
The photograph. It is the one asset genuinely shared across every listing of an unbranded object, because the resellers did not create it and have no reason to change it.
Vesim fingerprints that photograph with a 64-bit perceptual hash. Measured on 60 real product photographs: 98% recall with zero false matches across 1,762 true negative pairs.
Common questions
- Do Amazon ASINs solve this?
- Only inside Amazon. An ASIN is Amazon's own identifier and does not exist on Walmart, eBay or AliExpress, so it cannot join listings across marketplaces.
- Can titles be matched instead?
- Poorly. Marketplace titles are written for search ranking rather than description, so two listings of the same object routinely share almost no words, while two unrelated objects can share many.
Every factual claim here is one we measured or one you can check. Last reviewed 2026-10-23. How the matching works