I’ve been researching how inventory sync works across platforms like Shopify, Square, and Etsy. At first, it sounds simple. Someone buys a product on Shopify, so you reduce the stock on Square. Done, right? Not quite. Imagine both platforms show 10 items in stock, and two customers buy one at almost the same time, one on each platform. Both platforms update their stock to 9, but you actually have only 8 left. Then you have delayed webhooks, duplicate events, refunds, manual stock changes, and updates arriving in the wrong order.
I also looked at how Trunk handles this, and their approach makes more sense to me now. They keep their own inventory in the middle and use timestamped changes from each platform to figure out the correct stock. Basically, Trunk becomes the main inventory source. The interesting thing I’ve learned is that connecting APIs isn’t really the hard part. The real challenge is knowing what the inventory should be when several platforms are changing it at the same time. The deeper I look into inventory sync, the more edge cases I find. Still digging! 😂