Oversell
Definition
Overselling is accepting orders for more units than a store actually has, usually because several channels sell from the same stock and updates lag behind sales. The result is cancelled orders, refunds, and lost trust, and marketplaces penalise sellers for it. Preventing it takes one stock pool, reservations at checkout, and fast synchronisation to every channel.
Why it matters for your store
An oversold order is the worst kind of cancellation. The customer paid, expected the item, and hears days later that it does not exist. On a marketplace, the cancellation also counts against your seller score, which affects your ranking and, at some thresholds, your account.
The cause is almost always timing. Two channels each think they have the last unit, because the update from one has not reached the other. The more channels, the more windows. The fix is structural: count stock in one place, subtract at the moment a sale starts, and push the change out immediately.
Sometimes selling below zero is intentional, such as taking pre-orders for a restock. That should be a deliberate setting, not an accident.
How Kambloo handles it
All channels, the storefront and every connected marketplace, sell from one stock pool. When any order starts, a reservation is taken with a database row lock, so two simultaneous orders cannot both claim the last unit. Immediately after, the new sellable figure is pushed to every connected marketplace on a high-priority queue.
You can set a buffer per channel, for example report stock minus two to Trendyol, to absorb the seconds between a sale and the marketplace applying the update. If an oversell still happens on the marketplace side, the order enters an "awaiting stock confirmation" state and you are alerted, rather than the order shipping short.
A backorder setting, off by default, lets stock go negative on purpose. Orders taken that way are tagged as awaiting supply.
Questions about Oversell
Why do I oversell when I sell on Trendyol and my own site?
Because each channel sees a stock figure that is a few minutes old. A sale on one channel is not visible on the other until the next update. A single stock pool with immediate updates and a small safety buffer per channel closes the gap.
What is a stock buffer?
A per-channel margin you keep back. If you have ten units and a buffer of two for Trendyol, Trendyol is told you have eight. The two units absorb timing differences between channels.