Cartside
Checkout conversion up 18% after rebuild.
A storefront rebuild focused on page speed, mobile checkout flow, and a cleaner product discovery experience.
Summer Tee
$42
Linen Cap
$28
Canvas Bag
$65
Stripe Shirt
$58
Cartside's previous storefront was a heavily customised Shopify theme that had grown unwieldy — 14-second mobile load times on product pages, a checkout flow that broke on iOS Safari, and a product grid that couldn't surface personalised recommendations.
The client's AOV and traffic were strong; they were losing revenue purely at the conversion layer. We replaced the theme with a custom Next.js storefront connected to Shopify Storefront API, rebuilt the checkout flow, and introduced a lightweight recommendation engine.
The work
Next.js + Shopify Storefront API
Custom storefront built on Next.js with Incremental Static Regeneration for collection pages and dynamic fetching for cart and user state. Product pages load in under 350ms — replacing a 14-second baseline — while staying fully connected to Shopify's inventory, pricing, and fulfilment backend.
Mobile-first checkout rebuild
The checkout was extracted from Shopify's hosted checkout and rebuilt as a custom multi-step flow optimised for mobile. Address autofill via browser APIs, Apple Pay and Google Pay as primary payment options, and persistent cart state across sessions. The iOS Safari bug that was blocking 30% of mobile checkouts was eliminated entirely.
Product discovery and recommendations
A collaborative-filtering recommendation engine surfaces 'frequently bought together' and 'you may also like' blocks on product and cart pages. Built on purchase history data from Shopify's Analytics API, with no external ML vendor dependency.
The result
Checkout conversion climbed 18% in the first month post-launch. Mobile conversion specifically — the weakest segment before the rebuild — doubled. Average order value rose 12%, which the client attributed to the recommendation engine surfacing higher-value product combinations. The project paid back its cost in under six weeks of incremental revenue.
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Ready to build something like this?
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