Most online shops start with one supplier. A year later they have five, and the catalogue has become a warehouse of duplicates: the same product twice, each with a different price, a different name and different availability. The customer doesn’t know which one to buy, and comparison sites may penalise you for duplicate offers.
1. Unify the fields
Every supplier names things differently: PRODUCTNAME, title, nazev. The first step is mapping all feeds to one standard: name, description, EAN, code, manufacturer, price, stock, images, attributes. Watch out for character encoding and for prices with a decimal comma or with the currency in the text.
2. Merge by EAN, but carefully
EAN is the most reliable key for merging the same product from different suppliers. However, some suppliers use one EAN for a whole series (for example all hook sizes). Such shared EANs have to be recognised and not used for merging, otherwise ten sizes become one product.
3. Set the supplier order and availability
When several sources offer a product, decide which one wins. A proven rule: your own stock takes priority, then the supplier with the shorter delivery time. Mark a product you don’t have in stock but the supplier does as “in stock at supplier” with a realistic delivery time. Never send the supplier’s stock quantity to your online shop as your own.
4. Categories from your tree
Supplier categories don’t match each other. Map them to your tree by group and check that the groups are uniform. We cover this in more detail in our article on categories.
5. Automate updates
Prices and stock change every day. A one-off import is not enough: feeds have to be downloaded regularly, compared with the previous state, and if the product count drops suddenly, the output must be stopped before hundreds of products disappear from your online shop.