Custom Add-On System Built for Growth

A seamless upsell experience coded directly into Shopify, giving full control and zero recurring costs.

The Problem with Traditional Apps

We developed a fully custom add-on system using native Shopify features—no third-party apps or recurring charges.
Products intended as add-ons were grouped into dedicated collections, allowing for clean backend management.
Main products were linked to their respective add-on collections using a simple tag system (e.g., addon-fs-standard).
The logic dynamically displays relevant add-ons on the product page whenever a matching tag is detected.
This modular approach allows store managers to assign or change add-ons instantly by just editing product tags—no code edits needed.
The add-ons appear in a visually integrated layout, matching the store’s branding and offering a seamless upsell experience.

Developer working at a desk with code on screen

Smart Workflow & No-Code Updates Using Postman

We developed a fully custom add-on system using native Shopify features—no third-party apps or recurring charges.
Products intended as add-ons were grouped into dedicated collections, allowing for clean backend management.
Main products were linked to their respective add-on collections using a simple tag system (e.g., addon-fs-standard).
The logic dynamically displays relevant add-ons on the product page whenever a matching tag is detected.
This modular approach allows store managers to assign or change add-ons instantly by just editing product tags—no code edits needed.
The add-ons appear in a visually integrated layout, matching the store’s branding and offering a seamless upsell experience.

Seamless Frontend Integration

Add-ons are displayed directly on the main product page using a clean, responsive layout that blends with the site's theme.
Customers can easily select one or multiple add-ons without leaving the product page, improving convenience and UX.
Add-ons dynamically adjust based on the product’s assigned tag, making the experience context-aware and relevant.
The layout was coded to maintain fast load times and mobile responsiveness, avoiding the bloat caused by typical upsell apps.
Add-ons are treated as separate cart items, ensuring accurate inventory tracking and reporting within Shopify.

Smart Add-On Reminder System – Cart & Checkout

A dual-layer reminder system was created to increase attach rate of add-on products—displayed both at the cart stage and during checkout.
If no add-on items are in the cart, the system dynamically triggers:
1. A pop-up model upon clicking the “Checkout” button, nudging the user to consider extra gifts or essentials.
2. A dedicated carouselon the cart page titled Before You Go – Make it Extra Special with these Gifts”.
This setup ensures 100% visibility of add-ons at critical decision points, without overwhelming users.
The system is smart—only appears when relevant, based on real-time cart contents, ensuring a seamless and context-sensitive experience.
Add-on selection includes gifting items like vases, chocolates, teddy bears, all synced with delivery date options and “Add to Order” buttons.
Fully integrated with Shopify’s logic—no external apps, giving control and zero recurring costs.

Results & Takeaways

The custom add-on system delivered significant improvements in performance, flexibility, and revenue potential:

Zero Recurring Costs: Replacing paid apps eliminated monthly subscription fees, reducing long-term operational expenses.
Faster Site Performance: Removing third-party app scripts improved load times, especially on mobile.
Consistent Branding: Add-ons now fully match the site’s design—no more mismatched styling from external apps.
Increased Upsell Visibility: Strategic reminders at the cart and checkout stage boosted average order value without feeling intrusive.
Easy to Maintain: Store staff can manage add-ons directly via tags and collections—no dev work required post-launch.

This project demonstrates how custom development on Shopify can empower merchants to create tailored, high-converting experiences without relying on rigid third-party tools.

Thinking of replacing expensive apps with custom features?

Let’s talk. Hackney Digital UK can build smart, scalable solutions tailored to your store.

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