Magento has had native multi-location inventory since version 2.3, called Multi-Source Inventory (MSI): you define physical Sources (warehouses, stores, drop-ship vendors), group them into Stocks tied to specific sales channels, and Magento decides which Source fills each order using a Source Selection Algorithm. MSI tracks everything accurately as long as the stock only exists inside Magento. The moment inventory also lives in a separate warehouse system or sells through another channel, MSI has no way to know about it.
Sources are physical locations. Each Source represents a real place stock sits, a warehouse, a retail location, a third-party fulfillment center, with its own address and its own quantity per product.
Stocks group Sources and connect to sales channels. A Stock is a collection of Sources assigned a priority order, and each website in your Magento instance is assigned to exactly one Stock, which is how Magento decides where a given storefront's inventory actually comes from.
Reservations prevent overselling during checkout. Instead of decrementing the real quantity the instant an order is placed, Magento creates a Reservation record that reduces the salable quantity shown to shoppers immediately, then reconciles it against the actual Source quantity afterward, which keeps checkout fast under load without overselling.
The Source Selection Algorithm decides fulfillment. Open Source ships with one algorithm, Priority, which fills an order from the highest-priority Source with enough stock. Adobe Commerce adds a Distance Priority algorithm that can factor in how close a Source is to the shipping address.
MSI is genuinely good at what it tracks: Sources you've told it about, inside Magento. It has no visibility into a warehouse management system's own count, a 3PL's live inventory feed, or units that just sold on Amazon, eBay, or Walmart Marketplace through a listing that has nothing to do with your Magento store.
That gap is where overselling actually happens in practice. A product shows 12 units available in Magento because that's what MSI last knew, while 8 of those units sold on a marketplace an hour ago and nobody's told Magento yet. Nothing in MSI itself closes that loop; it has to be built.
When a 3PL or warehouse management system updates a quantity, that change reaches Magento's Source quantities automatically instead of waiting for someone to run a nightly import, so the storefront stops selling stock that's already gone.
If you also sell through Amazon, eBay, or another marketplace, a sale on any of them adjusts the same underlying quantity Magento uses, so a unit that sold somewhere else can't also get sold on your storefront before anyone notices.
Tell us which other system, a warehouse, a 3PL, another sales channel, holds a count Magento doesn't see. We'll look at what it would take to keep them matched automatically.
If a warehouse system, a 3PL, or another sales channel holds the real count and Magento only has what it was told last, that gap is exactly where overselling comes from. Tell us where the mismatch happens and we'll look at what's realistic to connect. Magento's inventory is one example of this; we build the same kind of sync for whatever system in your business still runs on a manual count.
Let's talk →MSI is Magento's native system, built in since version 2.3, for tracking stock across multiple physical locations (Sources) and deciding which location fills each order (Source Selection Algorithm). Both Magento Open Source and Adobe Commerce include it; Adobe Commerce adds one extra fulfillment algorithm on top.
No. MSI only tracks what happens inside Magento itself. A sale on Amazon, eBay, or another channel doesn't adjust Magento's stock count unless something, a marketplace integration app or a custom connection, explicitly syncs that number back in.
A Source is a physical location with its own quantity per product, a warehouse, a store, a fulfillment center. A Stock is a group of Sources in priority order, assigned to one or more websites, which is how Magento decides which Source actually fills an order for a given storefront.
Not natively. Magento's API lets an outside system read and write Source quantities, which is what any warehouse management system integration, including ones we build, uses to keep the two counts matched. There's no built-in connector that does this out of the box.