These comparisons do not rank platforms on postage price. What differs between platforms is what happens around the label: whether the tool tells you which service to pick, whether it runs natively on a phone, and how much manual comparison it saves you on an order that does not obviously favor one carrier.
The features that matter most cluster around three questions. Does the platform pick the cheaper carrier for you, or leave USPS versus UPS as a manual comparison on every order? Does it run as a native app, or only in a browser tab kept open at the packing table? And does it show every surcharge, dimensional-weight charge, and oversize fee before you commit to a label, or only after the invoice lands? Each comparison below answers those three questions for one named competitor.
Switching platforms is mostly a workflow change, not a postage change, so the honest way to evaluate it is by the hours it saves or costs on your actual order volume, not by a rate you were already paying the carrier. A seller doing a handful of orders a week may not notice a missing feature; a seller doing dozens a day feels a manual rate comparison, a missing bulk-import tool, or a browser-only workflow on every single one.
These 8 comparisons go feature by feature against the platforms sellers most often weigh I'd Ship That against. I'd Ship That prints discounted USPS and UPS labels from a web app and from native iOS and Android apps, and Ship Intelligence (Pro) automatically applies the cheaper valid carrier on orders where the two are close.
Pick the platform below you are actually deciding between; each page names the specific feature gap rather than a general claim of being better. If you are choosing a carrier rather than a platform, the carrier comparisons answer that question instead.