19 · Shopify Plus Development

Shopify Plus development for checkout, B2B, and Functions — not a faster theme.

Shopify Plus development for checkout UI extensions, Shopify Functions, native B2B, Markets, Flow, and ERP connections. We build the Plus surface the admin cannot — then hand the store to CRO and paid media on the same desk.

Checkout that converts. B2B that bills. Functions that replace dead Scripts.

Checkout ExtensibilityShopify FunctionsNative B2BUS-first · Markets

P&L desk
Reply in one business day
30-min working session

Schedule a call Request the brief

Desk fact

30 Jun 2026

Shopify Scripts stopped. New Plus logic is Functions — we will not rebuild on a dead API.

Desk fact

$2,300+

Plus platform fee Shopify publishes on a 3-year term. Development is a separate quote.

Desk fact

£15.4k

Replenhair cart + upsell revenue on the same conversion desk — no extra ad spend.

Stores

Stores on the same desk

Merchant logos from live Shopify work. Plus engineering sits next to this conversion book — we will not paste a Plus Partner wall we did not earn.

Direct answer

What is Shopify Plus development?

Shopify Plus development is the engineering work that only exists on Shopify's enterprise plan: Checkout Extensibility, Shopify Functions, native B2B, Launchpad, higher API limits, and expansion stores. SpikeROAS is that desk with a P&L attached — not a theme shop that put a Plus logo on the homepage.

US SERPs for this query are checkout, B2B, ERP, and migrations. They are not Dawn. checkout.liquid is gone on the checkout steps. Shopify Scripts stopped executing on 30 June 2026. New Plus work is Checkout UI extensions, Functions, and the Branding API. We will not start a project on a sunset API.

Shopify publishes Plus from about $2,300/month on a three-year term, or $2,500 on a one-year term. That fee is paid to Shopify. We quote the build. If you are still on Advanced and the leak is a slow theme, start with the Shopify development agency page. Plus is for the ceiling Advanced cannot clear.

Sources: Shopify Plus, Checkout Extensibility, Shopify Scripts sunset, and Shopify Plus B2B.

Fit

Who this Shopify Plus development agency is for

Merchants already on Plus, or operators about to pay Shopify $2,300+/month, who need checkout, wholesale, or integrations the theme editor cannot do. If you need a Dawn child theme, you are on the wrong page.

High-volume US DTC on Plus

Checkout UI extensions, post-purchase, Shop Pay, and Functions for discounts that Scripts used to run. The store has to take the traffic we buy — see ecommerce if the P&L is the brief.

Shopify Plus B2B and wholesale

Company accounts, catalogs, price lists, and net terms. Native Plus B2B — not a $200/month wholesale app glued onto Advanced.

Plus migrations and ERP

Onto Plus from Magento, custom, or a Plus store still running leftover Scripts. Redirects, Markets, and ERP / OMS / 3PL at Plus API limits.

Who we will not take

Brands that want Plus as a status badge. We will tell you if Advanced still fits.
Theme-only briefs. That is the Shopify development agency page.
Teams that want Hydrogen because it is fashionable. We pitch headless when Liquid cannot do the job.
Agencies shopping for unpaid white-label Plus labour with no access to the merchant.

The leak

What typical Shopify Plus agencies get wrong

Plus logo, Dawn underneath

A Premier Partner badge does not mean Checkout Extensibility shipped. We will show you the checkout extensions and Functions, or we will not take the work.

Scripts and checkout.liquid nostalgia

Scripts stopped on 30 June 2026. checkout.liquid is unsupported on the checkout steps. New work is UI extensions, Functions, and the Branding API. We will not rebuild on a dead API.

B2B as an app install

Plus has native companies, catalogs, and price lists. Wholesale apps on Advanced are a different product. We will not sell you Plus and then install the same app you already had.

Headless to inflate the SOW

Hydrogen + Oxygen is real when Liquid cannot express the UX. For most Plus catalogs, a fast OS 2.0 theme plus Checkout Extensibility still wins on cost and merchant editability. We will say which.

On the desk

Shopify Plus development services

US results for this query are checkout, Functions, B2B, migrations, and ERP. That is the menu. Theme-only work stays on the agency page.

Checkout Extensibility

Checkout UI extensions, the Branding API, and post-purchase. Upsells, fields, and trust in the checkout Shopify actually supports — not a checkout.liquid fork.

Shopify Functions

Server-side discounts, delivery, and payment logic. The replacement for Scripts. If your Plus store still 'has Scripts,' it does not. We rebuild the rules as Functions.

Shopify Plus B2B

Company accounts, catalogs, price lists, payment terms, and mixed DTC + wholesale. Native Plus B2B — not a wholesale theme skin.

Shopify Plus migration

Onto Plus from Magento, BigCommerce, custom, or a Plus store still on leftover checkout hacks. Redirects, Markets, Launchpad, and a tracking checklist.

ERP, OMS, and Plus apps

NetSuite, custom OMS, 3PL, and private apps at Plus API limits. Middleware when the App Store cannot carry the order volume.

Headless Shopify Plus with Hydrogen

Hydrogen on Oxygen, or Next.js on the Storefront API, when Liquid cannot do the job. We will not sell headless to dress up a theme rebuild.

Markets

Shopify Plus development in the US — and the Markets you sell into

Plus is a US enterprise product with a dollar fee. Markets, duties, and wallets are still local. We do not paste a US checkout into GST India and call it international.

Market

United States

Shop Pay, Shopify Payments, sales tax, and Plus checkout for high-volume DTC. Functions for US promo calendars. Hardware-scale catalogs only convert if checkout and the feed are honest — we have run Google Ads on a Florida hardware brand to $2.65M at 3.91x ROAS.

Market

United Kingdom

VAT, Shopify Payments UK, and Plus checkout in GBP. Replenhair is conversion proof on the same desk: £15,451 from cart and upsells with no extra clicks. Plus engineering is quoted separately from that cart work.

Market

Canada

GST/HST by province, Interac, and bilingual storefronts when Quebec is in the brief. Plus Markets so a Toronto checkout is not a New York checkout with a maple sticker.

Market

India

GST invoices, Razorpay / UPI, COD, and no-cost EMI. Crossword's custom cart had to carry Indian payment reality. Plus B2B is a different product if wholesale is the job.

Market

Australia

GST, Afterpay, Australia Post, and Shopify Payments AU on Plus Markets. Theme and checkout built for AU shipping promises — not a US store that 'also ships to Sydney.'

The work

What we actually do

Checkout Extensibility: UI extensions, Branding API, post-purchase — not checkout.liquid
Shopify Functions for discounts, delivery, and payment logic after Scripts stopped on 30 June 2026
Native Shopify Plus B2B: company accounts, catalogs, price lists, payment terms
Plus migrations and expansion stores with redirect maps, Markets, and Launchpad
ERP / OMS / 3PL integrations and private apps at Plus API limits
Hydrogen only when Liquid cannot do the job — honesty on headless cost

Deliverables

You leave with

Plus architecture brief: checkout, Functions, B2B, or Hydrogen
Staging checkout extensions and Functions on your Plus store
B2B company / catalog / price-list map
Launch checklist: pixels, CAPI, Shop Pay, Markets, speed

Ready to brief the Shopify Plus Development desk?

Send the Plus admin URL (or a staging preview) and the number that has to move. We will tell you what we would build — and whether you should stay on Advanced.

Schedule a call

Cadence

How the work runs

Audit Plus, not the theme

Checkout debt, leftover Scripts, B2B apps, API limits, and the conversion number.

Build on Checkout Extensibility

UI extensions, Functions, B2B, or a Plus migration — Hydrogen only with a measured reason.

Launch and hand to the P&L

Tracking live. Checkout green. Then CRO and paid can actually scale.

First 90 days

First 90 days on a Shopify Plus build

Days 1–14

Audit Plus, not the moodboard

Checkout extensions, leftover Scripts, B2B apps, API limits, and the conversion number. Architecture call: Extensibility, Functions, B2B, migration, or Hydrogen.

Days 15–45

Build on staging

UI extensions and Functions in your Plus store, in your name. B2B map if wholesale is in scope. Weekly staging URL. No surprise 'big reveal' at week eight.

Days 46–75

QA checkout and pixels

Shop Pay, tax, shipping, B2B login, and Core Web Vitals on real mobile. CAPI and Enhanced Conversions live so media is not blind at launch.

Days 76–90

Launch and hand to the P&L

Cutover, redirect QA, and a 30-day CRO + media plan. Plus is not 'done' at launch. It is ready to take traffic.

The fork

SpikeROAS vs typical Plus agency vs in-house

Hire us when checkout, B2B, or Functions have to move a number. Stay in-house when you already have Plus engineers and a checkout owner.

Factor	SpikeROAS	Typical agency	In-house
Scoreboard	Checkout conversion, AOV, contribution after the build	Partner badge and a Launchpad screenshot	Depends on whether Plus reports to marketing
Checkout	Extensibility and Functions — not checkout.liquid	App soup in checkout plus a branding coat of paint	Deep if you hired Plus engineers; thin if you hired a theme shop
B2B	Native companies, catalogs, price lists	Wholesale app on a Plus store	Strong if ops owns it; a mess if sales owns the price list in a spreadsheet
After launch	CRO and paid on the same desk	A Plus retainer that is really ticket labour	Roadmap fights with every team's feature request
Headless	Hydrogen when Liquid cannot; honesty when it can	Headless pitched to inflate the SOW	Often the right call if you already have React

Pricing philosophy

No fake menu. An honest gate.

Shopify Plus development is scoped as checkout, Functions, B2B, migration, or Hydrogen — not a theme tweak with a Plus line item. US Plus builds typically sit well into five figures once checkout and integrations are real. Shopify's platform fee is separate and paid to Shopify. We will not bid Plus checkout like a color swap.

You own the store, the apps, and the extensions. We do not hold the keys.
Theme work for a Plus store can live on the Shopify development agency page when checkout is not the job.
Best with CRO and performance marketing so launch week has a readout.
We do not resell Plus licenses.

The call

What happens in 30 minutes

30 minutes. Working session on the live Plus admin — not a moodboard.
Checkout leak, B2B, leftover Scripts, and whether Advanced still fits.
We will tell you Extensibility, Functions, B2B, or that you do not need Plus.

Schedule a call

Proof we will publish

Case studies live here — with numbers, not adjectives.

Named shopify plus development work is going on Work as we can show it. Until then, ask on the call for the scoreboard in your category. We will not invent logos or fake ROAS.

Your ad accounts stay in your name
Weekly kill / hold / scale memo
A 30-minute working session, not a pitch deck

Schedule a call See current work

FAQ

Questions we get about Shopify Plus Development

What is Shopify Plus development?

Shopify Plus development is engineering on Shopify's enterprise plan: Checkout Extensibility, Shopify Functions, native B2B, ERP integrations, and Plus migrations. It is not a standard Shopify theme with a Plus badge. SpikeROAS also runs CRO and paid on the same desk so checkout is scored on conversion.

How is this different from a Shopify development agency?

The Shopify development agency page is themes, store redesigns, apps, and migrations on standard Shopify. This page is Plus-only surface area. Google treats them as different queries. So do we. If you need both, we will say which ships first.

How much does Shopify Plus development cost?

Checkout extensions and Functions are typically a mid-five-figure US build once QA is real. Full Plus implementations with B2B and ERP run higher. Shopify's own fee starts around $2,300–$2,500/month depending on term. We quote the engineering. Shopify quotes the platform.

Do I need Shopify Plus or standard Shopify?

Standard Shopify (or Advanced) fits most single-brand stores. Plus earns the fee when you need full checkout customization, native B2B, higher API limits, or expansion stores. We recommend Plus when the feature set pays for itself — not as a status badge.

What happened to Shopify Scripts and checkout.liquid?

checkout.liquid is unsupported on the checkout steps. Shopify Scripts stopped executing on 30 June 2026. New Plus customization is Checkout UI extensions, Shopify Functions, and the Checkout Branding API. We build on that stack.

Can you customize Shopify Plus checkout?

Yes. That is Checkout Extensibility: UI extensions on information, shipping, and payment, plus post-purchase and the Branding API. We will not fork checkout.liquid. If an approved app already does the job, we will say so.

Do you build Shopify Plus B2B?

Yes. Company accounts, catalogs, price lists, and payment terms on native Plus B2B. Mixed DTC + wholesale when that is the operating model. A wholesale app on Advanced is a different product.

Do I need Hydrogen on Shopify Plus?

Only if Liquid cannot deliver the UX, CMS, or performance you can measure. Hydrogen on Oxygen is Shopify's official React storefront. For most Plus merchants, a fast OS 2.0 theme plus Checkout Extensibility is cheaper to run. We will not sell headless to inflate the SOW.

Are you a Shopify Plus Partner?

We engineer Plus stores. We do not wear a Partner badge we have not earned, and we do not resell Plus licenses. Shopify bills you for the platform. You own the store.

Do you run ads after the Plus store launches?

Yes. Checkout work that never sees a media plan is a brochure. Performance marketing and CRO sit on the same desk. We will still wire CAPI and Enhanced Conversions as if media is coming.

Usually paired with

Other desks on the same P&L

Shopify Development

Shopify development agency for custom themes, store builds, and migrations that convert.

Conversion Rate Optimization

Make the traffic you already bought pay rent.

Performance Marketing

Full-funnel paid that scales only when unit economics hold.

Email & Lifecycle

Flows that pay for the second order — so paid is not the only lever.

Industries

Where this service actually runs

Ecommerce & DTC

Next step

If Advanced cannot do the checkout, stop paying for a Plus logo.

Send the Plus admin URL (or a staging preview) and the number that has to move. We will tell you what we would build — and whether you should stay on Advanced.

Schedule a call Request the brief