Case Study · Shopify Checkout

Zero Manual Checkout Corrections

An apparel brand needed native Shopify checkout to run its tiered discount rules, offer delivery and pickup options that matched real inventory, and route every order to the right location automatically. We built four custom Shopify Functions and a Checkout UI Extension so all of that logic runs inside native checkout, not around it.

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An apparel brand

Apparel & Fashion

Shopify Plus
Checkout Extensibility

Custom Shopify Functions and Checkout UI Extension for apparel checkout

100%

Discount logic running natively in checkout

4

Custom Shopify Functions in production

Auto

Fulfillment routing by delivery address

Zero

Manual inventory allocation

Native

No checkout.liquid, upgrade-safe

Project Overview

About the Brand

An apparel brand sells online and through its own retail locations. Promotions are core to how it sells, with tiered bundles, category rules and exceptions that change by season, and a meaningful share of orders are collected in store rather than shipped.

Shopify's native checkout could take the order, but it could not express the rules behind it. Discounts had to be corrected after the fact, delivery and pickup options appeared whether or not they were valid for the cart, and someone on the operations team decided by hand which location would fulfill each order. Every one of those gaps was a manual step, and manual steps do not scale. The brief was simple: make native checkout behave the way the business actually runs.

Project Facts

ClientAn apparel brand

IndustryApparel & Fashion eCommerce

PlatformShopify Plus, checkout extensibility

Project ScopeCustom Discount Function, Delivery Option Generator, Checkout UI Extension, Fulfillment Constraint Function, theme app extension

Core WorkCheckout logic, delivery & pickup experience, inventory routing

Build4 custom Shopify Functions · 1 Checkout UI Extension · theme app extension

The Problem

Business Challenges

Checkout challenges for discount, delivery, pickup and fulfillment routing

Why us

Why They Chose Integriti Studio

Native-First Engineering

We keep business logic inside Shopify checkout with Functions and extensions, instead of bolting on apps that fight the platform.

Operations-Led Discovery

We mapped how the brand actually prices, picks, packs, and hands over orders before writing a line of function code.

Checkout Depth

Discount, delivery, and fulfillment constraint Functions plus Checkout UI Extensions, built in house and tested against real carts.

Upgrade-Safe by Design

No legacy checkout hacks. Everything ships on Shopify's supported extensibility surface, so future platform updates don't break it.

Our Process

How We Built It

Step 01

Operations Discovery

We sat with the merchandising and fulfillment teams to document every discount rule, delivery scenario, and pickup exception they were handling manually.

The Solution

What We Delivered

Four custom Shopify Functions and a Checkout UI Extension, working together so the checkout a shopper sees is already shaped by the brand's pricing rules, delivery reality, and inventory position.

Discount Function

Their discount rules, inside native checkout. We built a custom Discount Function that encodes the brand's own promotion logic and evaluates it on every cart at checkout. Pricing is correct before payment, with no app workarounds, no post-order corrections and no support tickets about the wrong total.

Delivery Option Generator

Delivery choices that match the order. A Delivery Option Generator builds and optimises the options shown at checkout based on the cart and the destination. Shoppers see the choices that can actually be honoured, which removes a whole class of exceptions from the operations queue.

Checkout UI Extension

Clear pickup guidance instead of failed checkouts. A Checkout UI Extension explains pickup availability in-line, at the moment the shopper is deciding. Where checkout previously threw an error, it now tells the customer what to do next, and the order completes.

Fulfillment Constraint Function

Inventory routed automatically by address. A Fulfillment Constraint Function assigns each order to the correct location based on the delivery address and stock position. Allocation happens at checkout, dispatch starts sooner, and nobody re-routes orders by hand.

Technologies and Tools

SFShopify Functions

UICheckout UI Extensions

TATheme App Extension

CLIShopify CLI

GQLGraphQL Admin API

SPShopify Plus

The Results

The Impact

100%

Discount Logic Running Natively

Every promotion rule now resolves inside Shopify checkout, so shoppers see the right price the first time and the team stops editing orders after the fact.

Custom Shopify Functions in Production

Discounting, delivery option generation, pickup guidance, and fulfillment routing are handled by purpose-built functions on Shopify's supported surface.

Auto

Fulfillment Routing by Delivery Address

Orders are allocated to the right location at checkout, with no manual allocation, faster dispatch, and fewer avoidable split shipments.

Fewer

Failed Checkouts on Pickup Orders

Pickup guidance replaced dead-end errors, recovering orders that previously dropped at the final step of the funnel.

Zero

Manual Inventory Allocation

Fulfillment decisions happen at checkout on Shopify's supported extensibility surface — upgrade-safe, with no legacy checkout.liquid hacks.

Start Your Project

Need a Checkout That Matches How You Actually Operate?

If your discounts, delivery rules, or fulfillment logic don't fit inside native Shopify, they can be built to. Tell us how your operation runs and we'll tell you what's possible on checkout extensibility.