There are five blue bowls on the shelf. Etsy shows five available, and your own shop shows five too. Once a bowl sells, you have four left. The other sales channel only knows this if the change reaches it. Two correct quantities can therefore stop matching your actual stock within moments.
When selling through several channels, you need a reliable relationship between the physical items, your listings and the orders received. Another connection can help. First, though, you need to establish which bowl belongs to which listing and which system determines the available quantity.
A product name is not enough to match items
The same item might be called “Blue ceramic bowl” on Etsy, “Breakfast bowl, sea-blue glaze” in your shop and simply “Small bowl” in your spreadsheet. A person may be able to connect those descriptions. An automated process cannot reliably tell whether all three represent the same stock.
A product identifier, often called a SKU, provides that connection. It identifies a particular version so that you can match orders and stock. Etsy explicitly supports these identifiers for organising inventory across sales channels; its SKU guide explains the principle.
Your initial mapping could look like this:
| Product identifier | Version | Shared physical stock |
|---|---|---|
| SCHALE-K-BLAU | Small bowl, blue glaze | 5 |
| SCHALE-K-GRUEN | Small bowl, green glaze | 8 |
| SCHALE-G-BLAU | Large bowl, blue glaze | 1 |
The small blue bowl needs to map to that version on every channel. A set of two bowls needs an additional rule, because selling one pack consumes two individual bowls. Entering the same text in a SKU field does not, by itself, connect the systems.
Each version you can actually supply matters
Colour and size affect stock when you store the finished items separately. Five small blue bowls and one large blue bowl are not six interchangeable bowls. Buyers should be able to order the particular version you can supply.
Personalisation is often a later operation on the same base product. If you engrave a name on a door sign, you do not keep every possible name on the shelf. You need to distinguish the material consumed from the production time you can still offer. Plenty of material does not automatically mean you can finish any number of orders by the promised date.
Etsy also distinguishes selectable variations from individual personalisation details. Its variations guide explains the settings. Check how a connected system transfers these details using your actual listings, rather than assuming both systems have identical options.
Which system is allowed to change stock?
If you correct a quantity independently in two systems, a later transfer may overwrite a newer value. The process therefore needs a clear owner: where is available stock maintained, and how do orders, stock counts and returns feed into it?
For a small range, a carefully maintained shared spreadsheet may initially be workable. With more orders in progress, a system that brings orders and availability together may be more appropriate. The important question is whether you can process the necessary changes reliably. A complicated inventory platform is not automatically justified by opening a second channel.
For the five bowls, your sellable quantity might be three if one has been ordered and another is reserved for a different order. Whether a basket already creates a reservation, and at what point, depends on the intended process. That decision belongs in the setup; otherwise, two systems may release the same item at different times.
What can happen between a sale and an update?
With a small range, you can deliberately allocate stock between channels: three bowls available on the marketplace and two only in your shop. You are then not offering the same freely available quantity in two places at once. That allocation still needs attention when you move stock or take an item back.
If each channel is to use the same stock instead, you need a suitable connection. It is not enough for a transfer to succeed eventually. You also need to recognise a missing update and know what happens to new orders in the meantime. Holding back a small buffer can reduce the risk during a delay, but it does not replace correct product mapping.
eBay also requires adequate stock when you sell through other channels at the same time, as explained in its selling practices policy. You therefore remain responsible for the process even when a connected application performs the updates.
A cancellation is not always the same as returned stock
If an order is cancelled before dispatch, the reserved item may be available to sell again. After a return, however, you first need to establish whether it has arrived and is still saleable. It would be inappropriate to make a damaged item available merely because a refund was issued.
An automated process therefore needs clear rules for these states. It should also avoid releasing stock twice when the same message is processed again after an interruption. A useful technical trial includes these situations rather than ending with the first successfully transferred purchase.
Make “we need an integration” a task you can check
To prepare, begin with a few different listings and the way you actually work with them. Useful examples include an ordinary product, a scarce variation and, where relevant, a set or personalised item. They let you show what should happen to the quantity after a sale, cancellation and return.
From there, you can define requirements a provider can demonstrate: the correct variation is matched, an order reduces the intended stock exactly once, a failed update is noticed, and a sold-out item is not left available by mistake. A broad promise to “sync everything” is of little help when assessing those behaviours.
If you want to add your own shop, we can work through this preparation with you. Under From marketplace to your own shop, describe the channels you use and where you currently maintain stock. If several systems are already connected but you still correct quantities by hand, Synchronising data between systems may also fit the task.
