What's the most complex Shopify Function you've built?

As more merchants move away from Shopify Scripts and adopt Shopify Functions, I’m curious about the real-world challenges developers are facing.

Which type of Function has been the most difficult for you to implement?

Custom discounts
Cart transformations
Delivery customizations
Payment customizations
Checkout validations
Something else?

What made it so challenging? Was it Shopify’s limitations, complex business logic, edge cases, or simply understanding the Functions API?

I ha love to hear your experiences and learn how others approached these problems.

@sophia24 ,
One of the more challenging Shopify Functions projects I worked on wasn’t actually related to discounts it was around product merchandising and catalog presentation for a large jewelry merchant.

The store has hundreds of thousands of SKUs and new diamond jewelry designs are uploaded in bulk every day. The problem was that products from the same design family would appear one after another in collections making the catalog look repetitive even though there were plenty of unique products available.

To solve this I built a private app that intelligently reorders the product listing. Instead of displaying similar designs consecutively it distributes them throughout the collection so shoppers see a wider variety of styles as they browse. It sounds simple but balancing randomness while ensuring products remain relevant and inventory-friendly was surprisingly complex.

Projects like this remind me that sometimes the biggest technical challenges arent checkout or discounts they are solving real merchandising problems that improve the customers shopping experience.

If you’re working with Shopify Functions, I’d also recommend checking out Nexus Functions Creator. It lets you build and manage complex discount, validation, and cart logic without writing Functions from scratch, making it much easier to handle advanced use cases and edge cases.