+21% Checkout Completion for a Global DTC Brand via Custom AI Sizing and Shopify Plus Optimization
SRFACE is a premium sustainable wetsuit brand based in the Netherlands, selling direct-to-consumer through a storefront powered by our Shopify Plus development services. The brand blends high-performance surf gear with a tech-savvy approach. It needed a development partner who could keep up with that goal.
The engagement covered five strategic pillars:
Each pillar tackled a specific growth issue. Together, they increased checkout completion and expanded global reach.
Client / Industry: SRFACE – premium sustainable DTC wetsuit brand (Netherlands, Shopify Plus)
Scope:
Tech Stack: Shopify Plus • Liquid • JavaScript • Node.js • OpenAI API • Python • Reviews.io • Intercom • Shopify Markets
SRFACE had an solid Shopify store development foundation and strong brand value. However, some technical and strategic gaps were slowing their next growth phase.
The sizing challenge wasn’t solvable with a static chart. Different body types and wetsuit models add to the complexity. Fit preferences, like tight performance and comfy recreational, also play a role. This made the decision tree too complicated for a simple table.
The solution: a “Get AI Size Advice” button on every product page, connected to a custom chat interface powered by OpenAI’s API.
POST /chat endpoint. It proxies requests between the Shopify storefront and OpenAI. It manages conversation context using thread_id, which has a 24-hour TTL.With the sizing barrier addressed, the next priority was eliminating friction from the purchase flow itself.
SRFACE’s growth plan needed a clear international rollout using Shopify Markets. This meant more than just adding new currencies. It required creating shopping experiences that are aware of different regions from the start.
Performance and discoverability work ran side by side with feature development. This wasn’t an afterthought; it was an ongoing priority.
Visual and interaction design improvements touched every major surface of the storefront.
Need AI personalization, global scaling, or high-end performance? We love a technical challenge. Let’s talk about your project.
Off-the-shelf sizing chatbots operate on generic decision trees. SRFACE’s products have fit profiles for each model, thickness variations, and regional sizing differences. No pre-built tool can handle these accurately. A custom OpenAI integration for Shopify lets us input real product schema data. This includes measurements, materials, and fit characteristics. By doing this, we can generate recommendations based on actual inventory instead of just estimates. The Node.js middleware for Shopify API also gave us full control over conversation context, rate limiting, and error recovery.
Third-party promotion apps on Shopify Plus typically inject their own JavaScript, add API calls on page load, and introduce dependencies that are outside your control during peak traffic. For a DTC brand optimizing for speed and conversion, that overhead is unacceptable. Building custom Buy X Get Y Shopify logic without apps – directly in Liquid templates and vanilla JavaScript – kept the promotional mechanics fast, predictable, and fully within the theme’s deployment pipeline.
Google’s shift from First Input Delay to Interaction to Next Paint as a Core Web Vital in March 2024 changed the competitive landscape for Shopify stores. INP measures the responsiveness of every interaction on the page – not just the first click. For a store with complex PDP interactions (size selectors, color swatches, AI chat, upsell modals), poor INP directly translates to perceived sluggishness and lost conversions. Addressing INP first had the highest impact-per-effort ratio for SRFACE’s specific traffic patterns.
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