JsRates: Custom Shipping Rates

JSRates gave us the flexibility to build shipping logic that we simply could not achieve with standard Shopify settings or visual rule-builder apps.

We used AI to help write all of the JavaScript, which made it possible for us to build a very advanced custom shipping system without hiring a developer. Our setup now handles refrigerated postal-code zones, frozen-product rules, package splitting, cart-value shipping allowances, remote-area surcharges, and fallback behavior if something goes wrong.

One of the biggest advantages is that JSRates can call a third-party shipping API directly to retrieve live carrier rates. In our case, we send our calculated package sizes, weights, origin, and destination to our external rate provider, then JSRates decides which returned carrier/service should actually be shown to the customer.

We also no longer need separate “hide shipping rate” Functions or apps. JSRates now handles the decision process itself and returns only the correct shipping option to Shopify.

Despite how complex the logic is behind the scenes, the checkout experience is very simple for the customer. We can offer things like Refrigerated Courier delivery only where it actually applies, while still falling back safely if a carrier rate is unavailable.

The app is also very developer-friendly. We were able to separate configuration, helper functions, postal-code data, third-party API logic, and the main decision tree into different files, which makes the whole system much easier to understand and maintain.

If you have shipping requirements that go beyond Shopify’s standard settings, JSRates is incredibly capable. It solved problems we had been struggling with for months. Highly recommended.