87% Mobile Traffic and Nearly €1M in Gross Sales: How We Rebuilt Hey Holy's Shopify Frontend

We worked with the German D2C brand Hey Holy, which produces premium dry dog food tailored to specific breeds (Beautiful Bulldogs, Precious Poodles, etc.).

When we joined the project, the online store was running on a standard Shopify theme. However, over time, as the brand ran frequent marketing experiments, the codebase had grown into a complex mix of CSS, Tailwind, and SCSS, with numerous custom templates and sections created for A/B testing. The client was planning a major redesign, wanted to increase conversion rates, and needed to implement sophisticated product recommendation logic.

We realized that Shopify's out-of-the-box capabilities were no longer enough. We needed to build a fast mobile interface capable of handling a constant stream of traffic while reliably processing recurring subscriptions.

Ready-made apps couldn't meet the brand's requirements, so we decided not to rely on third-party plugins. We stayed within the existing theme while building a feature-rich custom frontend and custom product recommendation logic.

We implemented an unconventional technology combination for Shopify: the lightweight Alpine.js framework and modular Web Components. This allowed us to build an interactive quiz, a dynamic calorie calculator, and a multi-discount system directly into the store without heavy third-party scripts.

1. Engineering Journey

Attempt #1 (Off-the-Shelf Shopify Apps): to implement multiple discount codes in the cart, we tested 5 different off-the-shelf apps from the Shopify marketplace one after another. However, none of these solutions met the client's requirements or satisfied the brand's needs, so we ultimately had to abandon them entirely.

Attempt #2 (Custom Micro-Engine): after testing five third-party apps unsuccessfully, we developed a custom multi-discount feature enabling users to easily apply multiple discount codes directly inside the mini-cart. The biggest challenge was supporting a continuous stream of weekly A/B tests without automated CI/CD — deployment involves connecting Git branches to themes and merging them live only after developer and QA approval. To avoid disrupting the Loop Subscriptions-powered subscription flow, we set up a rigorous manual testing process for every marketing update.

2. Custom Solutions

We designed three key tools:

Product-Finder Quiz: an interactive quiz built with Web Components and custom selection logic to help customers find suitable products.

Calorie Calculator: a custom calorie-based calculator built with proprietary selection logic.

Multi-Discount Engine: a multi-discount-code feature that allows users to apply several discount codes in the mini-cart.

3. Technology Stack and Specific Tools

Technology Stack: Shopify (custom Liquid theme) with a Vanilla JS, Web Components, and Alpine.js frontend, styled with Tailwind CSS v3 and SCSS for targeted animations, built with Laravel Mix v6 / Webpack.

Using Laravel Mix v6 as the Shopify theme build system, together with Alpine.js and Web Components, is highly unconventional for typical Shopify projects. This approach allowed us to achieve maximum frontend performance on mobile devices.

By developing unique frontend tools and eliminating heavy plugins, Hey Holy gained a stable platform with strong engagement metrics.

Technical outcomes

Clean, Conflict-Free Code: we built new custom modules with standardized, prefixed Tailwind CSS to ensure UI consistency without touching the existing theme's architecture.

Ongoing Maintenance & Stability: we provide continuous support for all custom modules (quiz, calorie calculator, and multi-discount system) through monthly maintenance, ensuring smooth releases.

Business outcomes

Mobile Optimization & Conversions: the website is fully optimized for smartphones, which account for 87% of all traffic, maintaining a stable 2.23% conversion rate.

High Customer Retention: reliable Loop Subscriptions integration supported the brand's exceptional 78.23% returning customer rate.