Inventory that agrees with itself.

Now — StockUnison is live on the Shopify App Store. Install it free on the store whose stock everyone should follow, connect a second store with the code it gives you, and you're syncing. Setup takes a few minutes and needs no call, no demo and no card; the setup guide walks every step. Support still comes from the person who writes the code.

Up to 250,000 product variants per store, and catalogue size is never priced — a large catalogue costs what a small one does. Matching reads both stores as a bulk job: a measured 100,000-variant catalogue comes back in about 45 seconds. Above 250,000, write to me before installing and I'll tell you honestly where the work stands.

There is a Free plan you can stay on: unlimited product matching, unlimited preview mode, the full activity log and difference checks — everything except writing to a connected store. Live syncing is $19/month for one connected store (Starter), $39/month for up to five (Growth), and $79/month for unlimited (Scale). Every paid plan has a 14-day free trial, and only the main store pays — connected stores always install free. Flat and public: no per-store creep, no feature ransoms, and billing runs through your Shopify invoice, so there is no card to enter.

Shopify only, by design: stock counts today, with products and prices next on the roadmap under the same guarantees. No marketplaces, no POS feeds — depth over breadth. If you're still weighing approaches, the guide on syncing inventory between two Shopify stores covers CSV and custom builds too, and Plus expansion stores have a guide of their own.

Yes — that's what shared stock is for. If you've listed the same item as several products (a mug on its own and in three bundles, a duplicate made for a campaign, the same jacket under two names), Shopify counts each one separately and they drift apart the moment anything sells. StockUnison puts every product carrying the same SKU into one group that holds a single count. One store on its own needs the Starter plan; the one-store-in-charge mode is the one that needs two or more stores.

One question: if a sale anywhere should lower the stock everywhere, share one stock. If only one store's count should be the real one and the others just follow it, put that store in charge. The app asks you exactly this on first run, and nothing is written in either mode until you've gone live — so picking the wrong one costs you a re-read, not your inventory. The help page has both walkthroughs.

Because it's built assuming you shouldn't. Connections start read-only, every write is previewed and logged, nothing is ever deleted without confirmation, and the drift report lets you verify — not trust — that your stores agree. There's also an honest comparison against the established apps, including where this one is the weaker choice, and the whole category side by side — what each app charges by, and what each one does when you leave.