If you have ever built a Shopify integration and started seeing weird inventory counts, duplicate orders, or fulfillments firing before payment confirmation — welcome to the club. The culprit is almost always the same: out-of-order webhook delivery. Shopify does not guarantee the order in which webhook events arrive. That one sentence should be in every Shopify integration tutorial. It rarely is. Let me break down why this happens and how to actually fix it. Why Events Arrive Out of Order Each webhook Shopify fires is an independent HTTP POST. No coordination. No sequence guarantee. Here is what causes ordering to break: Network latency — two requests take different paths, arrive in reverse Retry logic — a failed event retried 30 minutes later arrives after newer events Parallel workers — your consumer processes two events simultaneously; lighter one finishes first FIFO queue trade-offs — standard queues (SQS, etc.) don't guarantee strict ordering So you subscribe to orders/create and orders/updated .…