Multi-store inventory sync on Shopify
Two or three stores selling the same goods look like one problem and are really three: deciding who owns the number, moving it fast enough, and knowing later that it is still right. Most setups solve the first two and quietly skip the third.
Who owns the number
Stock can only have one owner. Usually it is the store connected to the warehouse, and the others display what it says. If two stores both write stock for the same product, they will fight, and the winner will be whichever wrote last - which is not a rule you can plan around.
One receiving store can be fed by several sources - a hub selling for three suppliers is normal - but each product in it must belong to one source. StoreTwin enforces exactly that, and sends the second claim to a review queue rather than letting the two overwrite each other.
Stock lives per location, not per store
A store does not have a stock number; each location does, and the storefront shows the sum of the locations it sells from. Syncing two stores therefore means choosing which locations in the sending store count, and which single location in the receiving store carries the total.
Get this wrong and everything looks broken while being arithmetically correct. The mapping choices, in detail.
Speed is the easy part
Webhooks carry a change within seconds, and every app in this category does that. The interesting question is what happens to the change that did not arrive: an app restart, a network blip, a rate limit. If nothing ever compares the two stores again, that product stays wrong forever.
StoreTwin re-checks changed products every hour and the complete catalogue every night, so a missed event becomes a line in a report instead of a permanent difference.
Three stores, not two
With more stores the failure modes multiply, and two rules keep the arrangement sane. First, no rings: if A feeds B and B feeds C, then C must not feed A, or an edit travels round and comes back to where it started. StoreTwin refuses to pair stores into a ring at all.
Second, every receiving store is a separate connection with its own product selection, so one market can carry a shorter range without affecting the others.
How to check today's numbers
Pick a product, open it in every store, compare per location, and then look at what your app claims about that same product. If the app cannot show the two values side by side, the answer to "are we in sync" is a guess.
StoreTwin's free plan audits a catalogue of any size, including one another app is syncing, so you can measure your current setup before changing it. How the audit works ยท Pricing