Learn / Fixes
How to add GTINs to your catalogue
A GTIN is a global identifier that lets an agent recognise your product as the same item it has seen on another store, which is what makes a price comparison possible at all. Without one you can still be found, but you are compared as an unknown rather than as a competing offer on a known product, and unknowns lose.
A GTIN is a global identifier that lets an agent recognise your product as the same item it has seen elsewhere. That recognition is what makes a price comparison possible: without it you are not a competing offer on a known product, you are an unknown that happens to have a similar name.
This is the fix for missing GTIN.
Why identity matters more than description
Two listings of the same jacket can differ in title, photography, description and category. An agent asked to find the best price on that jacket has to decide whether they are the same thing. Text matching is a guess. An identifier is not.
If you are the cheaper of two offers on an identical product and only the other one publishes an identifier, you may simply not be in the comparison that you would have won.
They belong on the variant
A GTIN identifies a specific sellable item, which means a size and a colour combination has its own. Putting one identifier on a parent product is a common error and a damaging one: it asserts that every variant is the same item, which matches all of them to whichever the identifier actually belongs to.
This is closely tied to variant level data generally. See no variant data.
Where to find them
- For resold products, in supplier data you already receive. Very often the values are in your systems and stop before the storefront template.
- For own brand products, from GS1, which issues them.
- Nowhere else. Do not derive one, do not reuse one from a similar product, and do not fill the field to make a validator pass.
When a product genuinely has none
Some products have no GTIN and never will: bespoke items, made to order goods, services. The correct handling is to state that the field does not apply rather than leave it silently absent, so the absence reads as a fact about the product rather than as missing data about your store.
Publish them in both places once you have them: in your product schema and in your feed. An identifier in one and not the other creates exactly the ambiguity it was meant to remove.
Questions
What if my products are own brand and have no GTIN?
Then say so explicitly rather than leaving the field empty or inventing a value. An own brand product is genuinely not the same item as anything else, so the comparison it needs is on attributes rather than identity. Making up an identifier is worse than having none, because it can match you to the wrong product.
Where do GTINs come from?
For products you resell, from the manufacturer or the supplier data you already receive. For products you make, from GS1, the body that issues them. Most stores find the values already exist somewhere in their systems and simply never reach the storefront.
Does the GTIN go on the product or the variant?
The variant, always. A GTIN identifies a specific sellable item, so a size and colour combination has its own. One GTIN on a parent product is a common and quiet error that matches every variant to whichever one happened to be first.