Shopify Custom Apps & Functions Development
When Shopify's built-in features and off-the-shelf apps can't do what your business needs, a custom app or a Shopify Function can. I build private and custom apps — admin extensions, integrations with ERPs, 3PLs and marketplaces, automation and reporting — plus native Shopify Functions for discount, shipping, payment and cart logic that runs inside the checkout.
What’s included
The scope of this work
- Custom and private Shopify apps: admin UI extensions, internal dashboards, and business logic Shopify doesn't offer natively
- Integrations: ERP, 3PL/WMS, PIM, accounting, marketplace and custom data feeds, built on the Admin API and webhooks
- Automation beyond Shopify Flow: scheduled jobs, bulk operations, and multi-step workflows
- Custom discount Functions: tiered, volume, bundle and cart-level promotions beyond native discounts
- Delivery and payment customization Functions: hide, rename or reorder methods based on cart, customer or address
- Cart and checkout validation Functions, plus migration of legacy Shopify Scripts to native Functions
How it works
From brief to live
We define exactly what the app or Function needs to do — data in, data out, edge cases, and who uses it — before any code.
I build it against a dev store, with staged previews so you can see it working before it touches production.
Deployed with monitoring and error logging, plus a handover doc so your team knows how it runs.
FAQ
Custom Apps & Functions: common questions
What counts as a "custom app"?
A private app built for your store alone — not something on the Shopify App Store. It might add screens to your Shopify admin, sync data with another system, or run business logic on a schedule. You own it, and it does exactly what you need and nothing more.
Do I need Shopify Plus for this?
No. Custom apps and discount, delivery and payment Functions work on every Shopify plan. A few checkout-specific extension points are Plus-only — I'll tell you upfront which parts of your requirement need Plus.
I still have Shopify Scripts running. Do those need to move?
Yes. Shopify has retired the Script Editor app, and Scripts stop running after the platform sunset date. Anything you rely on for discounts, shipping or payments should be rebuilt as a Function — I handle that migration end to end.
Can you connect Shopify to our ERP, 3PL or other system?
Usually, yes. Most systems have an API or support file-based feeds. I scope the integration — what syncs, how often, and what happens when something fails — before committing to it.
How is this priced?
Fixed-scope projects quoted after a spec call. Larger builds are scoped as a sprint. See the pricing guide on the main services page.
Related work
Where this has come up
Delivered B2B discount functionality, birthday sales management, and custom landing pages for Elyte Hydration, alongside Skio integration and Shopify Flow automation setups.
Supplements · New ZealandLed a theme upgrade and conversion-focused storefront redesign for LMCHING GROUP using the Horizon theme, focusing on conversion optimization, and implemented Shopify Flow to automate key store tasks.
Cosmetics · Hong KongGot a Shopify Project Brewing?
Let's talk it through. Book a free call and I'll tell you exactly where to start.