Step Functions for Cart and Fulfillment: Async Workflow Patterns That Survive Production
Every e-commerce team starts with a synchronous checkout. The API receives a cart, charges the card, decrements inventory, and returns a confirmation. It works until it doesn't. Payment processors time out. Warehouses operate on batch cycles. Inventory reservations race against each other across regions. I have rebuilt checkout and fulfillment pipelines three times across different organizations, and every rebuild ended at the same place: an asynchronous state machine with compensating transactions. AWS Step Functions is the right tool for this job, and this article covers the specific patterns, cost math, and operational lessons from running cart-to-delivery workflows in production.