Plenty of online brands pick a warehouse the way they’d pick a dentist in a hurry: whoever answers first. It usually happens in a panic, a few weeks before the holidays, and it tends to get expensive. They can also pile on hidden fees, slow your shipping, and turn returns into a mess if you choose badly. This guide explains what ecommerce fulfillment companies actually do, what they cost in 2026, and what to ask before you sign anything. In plain terms, they run the physical side of your online store so you don’t have to.