Platform Product vs Product

The core split in the data model: one Platform Product per SKU holding stock and identity, and one Product per SKU per marketplace holding that channel's content and sync state.

Nearly every question about how MarketplaceHub behaves comes down to one distinction: the thing you stock, and the listings that represent it on each marketplace. They are separate records, and knowing which one you are looking at explains most of what the app does.

Platform Product — the SKU

A Platform Product is one row per SKU for your whole account. It is the hub. It carries:

• Sku — the identifier everything else matches on. SKU is the join key across the entire system: price and stock updates, feed imports and marketplace sync all find products by SKU, not by any internal id.
• Quantity — the stock figure of record. One number, not one per channel.
• CategoryIDs — which of your own category folders it sits in.
• ExternalIds — the native id the SKU has on each marketplace it already exists on.

That last field is what stops duplicate listings. When MarketplaceHub already holds an external id for a SKU on a given marketplace and country, publishing revises the listing that is already there instead of creating a second one.

Product — the listing

A Product is one row per SKU per marketplace and country. If you sell the same SKU on Amazon UK and eBay UK, that is one Platform Product and two Products.

Each Product carries the things that are specific to that channel:

• The attribute values for that marketplace's schema, held as a list of values rather than fixed columns — because the required fields differ per product type. See the feed field reference for what a given product type expects.
• Which product type the listing is filed under on that marketplace.
• Its own sync status, tracked separately for content and for price/quantity, so a stock change can be pushed without republishing the whole listing.

Why the split matters in practice

Three behaviours follow directly from it:

• Stock is held once. A stock change updates the Platform Product, then each connected marketplace's Product is marked as needing a push. You never reconcile four different stock numbers.
• Content is per channel. The same SKU can carry a different title, different attributes and a different category on Amazon than on Etsy, because those live on the Product, not the SKU.
• A marketplace can be added later without re-importing. Connecting a new channel creates new Products against the Platform Products you already have.

Variants

Parent/child products — a shirt in four sizes — are expressed in your feed with parent-sku, parentage and relationship-type columns, and become variant records under the parent. See the product feed format.