Stock Sorted

Stock Sorted is my own product, and the project where I get to do the whole thing from 0 to 1: discovery, positioning, design, engineering, launch and support.

Discovery. The problem came from merchant forums, not from my imagination. Merchants running multiple Shopify stores kept asking the same question: how do I share one inventory across them? Shopify has no native answer, and the workarounds people traded in those threads were fragile and manual. That’s a real pain with money attached.

Why it’s hard. Shared inventory is a textbook concurrency problem. Two stores can sell the same last item at the same moment, and a naive sync oversells it. Merchants hit this race condition in the middle of massive product drops and can’t solve it directly on Shopify. I wrote up the details in Shared inventory on Shopify: why it’s harder than it looks. The short version: this needs to be solved properly at the sync layer, which is why I built it in Elixir, a language made for exactly this kind of problem.

Delivery. Stock Sorted is live on the Shopify App Store with paid plans, syncing real merchants’ inventory in production. The design, the code, the listing, the analytics and the support inbox are all mine. There is no better way to stay honest about your design decisions than answering the support emails they generate.

Results. The official store of Kashima Antlers uses Stock Sorted. Kashima are the 2025 J1 League champions and record title holders, and their store processes several thousand orders per hour during product launches. A traffic spike exposed a technical issue during their first launch with the app. I fixed it, and their 5 star review reports zero inventory discrepancies on the second.