Shopify Custom API Development

Your B2B operation, proprietary back-office system, or custom checkout logic falls outside what any certified connector or Shopify app can handle. Standard tools make assumptions about your data model that your operation breaks. Shero develops against Shopify's REST and GraphQL APIs for requirements the app ecosystem cannot meet.

Book a Discovery Call Our Work

16+

Years in business

500+

Projects Delivered

65+

Team Members

98%

Client Retention

Help Scout

HelpScout webhook that tags customers by class

When a Taking Cara Babies customer buys a class, a webhook we developed tags them in HelpScout with that class. The tag shows on every support ticket, and their case study covers the rest of the integrations.

Query cost

How Shopify limits API calls

Shopify's GraphQL Admin API limits apps by query cost, and Shopify Plus stores get a higher limit. We write ERP integrations to stay under it and use bulk operations for large catalog syncs.

Scripts to Functions

Shopify Scripts retired

Scripts stopped executing June 30, 2026. All custom checkout logic must be in Shopify Functions. Shero migrates existing Scripts and creates new Functions.

Kuebix

Live freight rates at checkout for GEN-Y Hitch

We made GEN-Y Hitch a custom app that pulls live parcel and LTL freight rates from its Kuebix system into checkout, with dealer-specific rules. Shopify has no native freight rating, so the app does that job.

"This has been the most impressive vendor partnership I have experienced. Every meeting felt purposeful, every milestone was clear, and the process was incredibly well-supported from start to finish."

Kendra Borkholder, Operations Support, GEN-Y Hitch

Custom Shopify API development versus configuration

Custom API development is the right approach when no app covers the requirement, when a connected system has a non-standard data model, or when checkout logic needs to execute inside Shopify using Functions. Shero develops against the Admin API for back-office data, Storefront API for headless requirements, Shopify Functions for checkout and discount logic, and Webhooks for event-driven automation.

Shopify Admin API
Shopify Storefront API
Shopify Functions (checkout, discounts, shipping)
Webhooks and event-driven flows
Private and custom app development
API version management and maintenance

Compared on	Shopify API development agency	A public app from the App Store	A freelance developer	An offshore dev shop
Outside systems and APIs	Regal Cinemas: Crown Club credits and a weekly movie feed from Regal's API tied to Shopify	Only if an app exists for your system	Possible, one person to maintain it	Made to your spec
Bulk data jobs	Camera Source: catalog, customers and orders moved to Shopify, with a delta import on launch day	Limited to the app's import tools	Scripts, checked by hand	Fast, with your team checking the data
API rate limits at peak	Queues and retries designed for Shopify API limits	Handled by the app vendor	Depends on their Shopify API experience	Covered if written into the spec
Orders out to your 3PL	Orders pushed to your 3PL or ERP by webhook	Common 3PLs covered by apps	Custom code they look after	Custom code you look after
How you pay	Paid discovery, then an accurate estimate.	A monthly app subscription	Hourly	A fixed bid per spec

Shopify API development agency

Outside systems and APIs Regal Cinemas: Crown Club credits and a weekly movie feed from Regal's API tied to Shopify

Bulk data jobs Camera Source: catalog, customers and orders moved to Shopify, with a delta import on launch day

API rate limits at peak Queues and retries designed for Shopify API limits

Orders out to your 3PL Orders pushed to your 3PL or ERP by webhook

How you pay Paid discovery, then an accurate estimate.

Compared with

A public app from the App Store

Outside systems and APIs Only if an app exists for your system

Bulk data jobs Limited to the app's import tools

API rate limits at peak Handled by the app vendor

Orders out to your 3PL Common 3PLs covered by apps

How you pay A monthly app subscription

A freelance developer

Outside systems and APIs Possible, one person to maintain it

Bulk data jobs Scripts, checked by hand

API rate limits at peak Depends on their Shopify API experience

Orders out to your 3PL Custom code they look after

How you pay Hourly

An offshore dev shop

Outside systems and APIs Made to your spec

Bulk data jobs Fast, with your team checking the data

API rate limits at peak Covered if written into the spec

Orders out to your 3PL Custom code you look after

How you pay A fixed bid per spec

01

API selected based on the requirement, not habit

Shopify has several distinct APIs. Shero selects the correct one for each requirement: Admin API for back-office data, Storefront API for frontend and headless, Functions for checkout logic, Webhooks for event-driven automation.

02

Shopify Functions replace Scripts as of June 2026

Shopify Scripts stopped executing on June 30, 2026. All custom checkout, discount, and shipping logic now has to be written in Functions. Shero migrates existing Scripts and writes new checkout logic in Functions from the start.

03

Business logic documented before development begins

Custom API integrations fail when edge cases show up during development. Shero documents the complete business logic, error conditions, and workflow exceptions before writing any code. This produces an accurate scope.

04

B2B custom logic for pricing, accounts, and checkout

Shopify Functions replace Shopify Scripts for custom discount, payment, and shipping logic in Shopify Plus. B2B custom pricing is a common use case for Shopify Functions, covering volume discounts, account-level price overrides, and catalog-specific discount logic.

05

API version management across Shopify's deprecation schedule

Shopify deprecates API versions on a defined schedule. Shero manages API version updates for every custom integration it develops. Integration assessment includes an API version audit for brands with existing custom integrations that may be on deprecated versions.

06

Documentation handed over so your team understands what was delivered

Shero delivers integrations with endpoint specs, data flow diagrams, error handling guides, and version management plans. The documentation is complete enough for an internal team or future agency to maintain.

Digital products

Ordergroovedigital memberships with free trials and plan changes, connected through custom middleware

Stripesubscriptions and saved cards moved off Stripe at go-live

Shift WorshipShopify

Entertainment

Custom appcredit based checkout rebuilt in a custom Shopify app

+40%faster page loads than legacy Magento

Regal CinemasShopify

Read the case study

Backup camera systems

+32%Google clicks in the 12 weeks after the move from Magento

+65%Google impressions, same 12 weeks vs the 12 before

Camera SourceShopify

Read the case study

Lacrosse and Hockey Gear

STX

Looking to scale alongside growing global markets and competitor consolidation, the premium American manufacturer of lacrosse, field hockey, and ice hockey equipment, partnered with Shero to migrate from Adobe Commerce (Magento) to Shopify, delivering a unified D2C and B2B experience, custom ERP integration, and a refined storefront that reflects the engineering quality of their products.

STX

Premium Knives

Benchmade

For more than three decades, Benchmade has been known for producing high-quality knives for everyday carry, hunting, rescue, and outdoor use. Launched on Magento Commerce Cloud in 2018, the brand partnered with Shero to expand online amid rising outdoor consumer demand. Since then, they have seen: +100% revenue growth, +68% transaction growth after relaunch, and a +20% increase in average order value.

Benchmade

Musical Instruments

F-Musiikki

F-Musiikki is one of Finland's leading music instrument retailers, serving both consumers and businesses with over 15,000 products. Looking to reduce costs and modernize their platform, the brand partnered with Shero to migrate from Magento to Shopify Plus and launch a hybrid B2C/B2B store in just two months.

F-Musiikki

Movie Theaters

Regal Cinemas

One of the largest cinema chains in the US, Regal Cinemas, partnered with Shero to migrate from Magento to Shopify, building a 100%Credit-based checkout logic replicated in a custom Shopify app, loyalty reward redemption, Vista Cloud integration, and automated corporate gifting workflows across two distinct eCommerce platforms. As a result, they achieved over 40% faster page load time.

Regal Cinemas

Built to load fast and stay fast

Every build goes live with the speed and code standards that keep the store fast after launch.

Core Web Vitals
Templates built and tested to pass on mobile.
Fewer apps
Features built into the theme when an app would slow the store.
Clean code
Online Store 2.0 sections your team can edit without a developer.
QA
Every release tested on desktop, mobile and checkout.

Custom Shopify API projects take 6 to 16 weeks. Tell us what must connect.

Scope my custom API project

01

Discovery
In recorded workshops we write down your business rules, edge cases and errors, match each one to the right Shopify API, and agree scope and acceptance criteria.
02

Spec
The spec covers GraphQL queries, webhooks, field mappings, error handling and the API version we target.
03

Develop
We develop with field validation, retry logic and logging, and keep the new sync off until launch day.
04

Testing and UAT
We test failure cases, rate limits and timeouts on purpose, trace the first live order through every system, and you sign off in UAT.
05

Go-live and hypercare
You get endpoint docs and data flow diagrams, we stay on through hypercare, and we update the code ahead of each Shopify API version change.

Frequently asked questions.

Can't find what you're looking for? Reach out to our team.

01

When should we use custom API development instead of an app?

Custom API development is right when no certified connector covers the requirement, when the connected system has a non-standard data model, when business logic needs to work inside Shopify's checkout using Functions, or when long-term control over the integration code is a priority. Shero makes this recommendation in discovery with cost and maintenance trade-offs explained.

02

What happened to Shopify Scripts in 2026?

03

What are Shopify Functions and when are they needed?

Shopify Functions are custom logic blocks that execute inside Shopify's checkout, discount, shipping, and payment systems. They replace Scripts as the correct approach for B2B payment term logic, volume discount rules, and custom shipping calculations. Functions execute without external API calls, which means faster execution and no failure risk from external dependencies.

04

How do you manage custom integrations when Shopify releases a new API version?

Shopify releases a new API version every quarter and supports each one for at least 12 months. Shero manages version updates for custom integrations under ongoing support arrangements, updating API calls before deprecation affects production. At handoff, Shero documents the version management requirements for clients taking full ownership of the code.

05

How long does a custom Shopify API integration take to develop?

06

Will we receive documentation we can use if we change agencies?

Shero delivers integrations with endpoint specifications, data flow diagrams, field mapping tables, error handling guides, and version management plans. The documentation is complete enough for your internal team or a future agency to understand, maintain, and extend what was set up. For related services, see our iPaaS and middleware and Shopify CRM integration pages.

What our clients say.

We design experiences that make a difference. See what our clients have to say about working with us.

STX

"Since partnering with Shero Commerce, our eCommerce revenue has grown by 200%. Their 24/7 support and innovative solutions have been game-changers for our business."

James McKenna

Senior Commerce & CX Manager / STX

Painful Pleasures

"Our journey from Magento to Shopify was riddled with complexities and challenges. With a vast catalog and intricate B2B logic, we needed expertise that could navigate through these intricacies. Shero Commerce was our beacon. They not only provided innovative solutions but also utilized their vast Magento knowledge to bridge gaps in Shopify’s native features. Now, our platform is seamless, our costs are reduced, and the headaches are a thing of the past. A heartfelt thank you to the Shero team!"

Patrick Rice

CEO / Painful Pleasures

Swag Golf / Strike 2

"We partnered with Shero for the development work on the SWAG site. The dev was highly nuanced, specialized and complex—and the brand demanded a UX that was smooth, straightforward and memorable. The Shero team went above and beyond from the jump. As a partner to us, they were collaborative, organized and professional. As a partner to our client, they consistently set expectations clearly—and usually exceeded them. We were immediately faced with the challenge of getting this site up on a faster timeline than any similar project we’ve done before. Because of Shero’s tight process and expert dev talent, hitting this deadline was a walk in the park. And most importantly they are a group of terrific people and were a delight to work with. I can’t wait for our agencies to partner again."

Matt Kaminsky

Co-founder & Managing Director / Swag Golf / Strike 2

Justrite Safety Group

"The collaboration between us and Shero Commerce on the Justrite multi-store site went beyond what we had hoped for. They are a terrific partner to work with. Their team’s dedication to understanding our unique requirements and delivering a high-quality, customized solution has greatly enhanced our online presence. The new website not only showcases our products effectively but also streamlines the shopping experience for our customers. We couldn’t be happier with the results and look forward to working with Shero Commerce on future projects."

Douglas J. Stang

VP of eCommerce / Justrite Safety Group

And you?

Let's build something great together.

Ready to scale your eCommerce business? Tell us about your project and we'll get back to you within 24 hours.

Email

[email protected]

Locations

New York • London • Helsinki • Tirana

Shopify Custom API Development

Custom Shopify API development versus configuration