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Shopify PlusCheckout ExtensibilityB2B on ShopifyHydrogen

Shopify Plus Development

The Shopify Plus development agency for brands that use the whole platform

Checkout extensibility, Shopify Functions, B2B company accounts, expansion stores, and ERP integration, engineered in version control, documented, and built so the next team can maintain it.

  • Checkout UI Extensions and Shopify Functions, not forked checkout.liquid
  • Integration scoped as discovery, because that is where Plus builds slip
  • Staging, code review, and a deploy path you can reverse
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What Plus actually changes

Shopify Plus is a different engineering surface, not a bigger plan

Shopify Plus is a different engineering surface from standard Shopify. The checkout becomes programmable through extensions and server-side Functions, which is the base for our Shopify checkout optimization work. The store can serve B2B buyers on Shopify and DTC customers from one instance with different pricing and terms, expansion stores turn a single storefront into a portfolio, and API limits rise to the point where real-time integration with an ERP or OMS becomes practical. That surface is the reason brands upgrade, and our Shopify Plus pricing guide covers the platform fee. It is also the reason Plus builds go wrong more often than standard Shopify builds do: more capability means more places for state to diverge, more systems that must agree with each other, and more code paths that only execute for a subset of customers.

The agencies that do this well are distinguished by process: version control on the theme, a staging environment that mirrors production closely enough to be meaningful, code review on anything touching checkout or pricing, and a deploy path that can be reversed. We build on Shopify Plus with that bias, as the engineering side of our Shopify Plus agency. Different categories push complexity into different parts of the build, and knowing where it will land changes how a project is scoped. We will tell you when a capability you are paying for is not the one that will move your revenue, when headless Shopify Hydrogen is the wrong trade, and when a lower plan built by our Shopify development agency already solves the problem.

What we usually find

The problems that bring brands to a Plus development agency

These are the recurring patterns in Plus stores that have grown faster than their engineering process. None of them are unusual, and none of them are unfixable.

  • Checkout customisations that break on every platform update

    Legacy checkout.liquid customisations are a fork of Shopify's checkout, which means every platform change is a potential regression. Checkout extensibility replaces that with versioned, sandboxed extensions and server-side Functions. Brands still on the legacy path should treat migration as scheduled work, not as an emergency response to a breakage.

  • An app stack that has become the architecture

    It is common for a store that grew quickly to be running fifteen to thirty apps, several of which inject scripts into the same page and two of which do roughly the same job. The cost shows up as page weight, as conflicting behaviour that is difficult to reproduce, and as a monthly bill nobody has audited. Consolidation is usually cheaper than it looks and pays back in performance.

  • Integrations that are technically working and practically unreliable

    Inventory that is accurate most of the time, pricing that is correct until a sync fails silently, order data that reconciles except at month end. These are not integration failures in the sense of throwing errors; they are failures of observability. If nobody is alerted when a sync does not run, the integration is not finished.

  • A theme only one person understands

    Plus stores accumulate customisation, and customisation without documentation or version control concentrates knowledge in whoever happened to write it. The risk is not abstract: it surfaces the first time that person is unavailable during a peak trading week. Getting the theme into version control with a real review process is the single highest-leverage change most Plus stores can make.

  • B2B bolted onto a DTC store

    Wholesale customers served through discount codes, manual invoices, and a spreadsheet of agreed prices. It works at low volume and becomes a liability as it grows, because the pricing logic lives in people's heads rather than in the platform. B2B on Shopify moves that into company accounts, catalogs, and price lists that the store itself enforces.

  • Nobody can say what a release is going to do

    Where changes are made directly in the theme editor on the live store, every deploy is an act of faith. Staging environments, branch-based workflows, and a rollback path turn releases from events into routine. This is the least visible thing an agency can improve and frequently the most valuable.

Shopify Plus development services

What we build on Shopify Plus

The Plus surface is wide. These are the areas where the platform does something a lower plan cannot, plus the engineering work that makes any of it maintainable.

  • Checkout extensibility

    Checkout UI Extensions for upsells, trust content, delivery instructions, and custom fields in Shopify's supported checkout slots, versioned and upgrade-safe rather than forked from checkout.liquid.

  • Shopify Functions

    Server-side logic for discounts, shipping method visibility, payment method rules, cart transforms, and bundles. Runs on Shopify's infrastructure, which means it applies consistently rather than depending on a script executing in the browser.

  • Shopify Plus B2B development

    Company accounts, multiple buyers and locations per company, per-company catalogs and price lists, payment terms, and quantity rules, with DTC and wholesale running from one instance and one product catalog.

  • Expansion stores and Markets

    Additional storefronts on the same Plus contract for new regions, brands, or business models, with a deliberate decision about what is shared (catalog, code, content) and what is local. Markets configuration covers multi-currency, multi-language, and regional catalog and pricing, with domain, hreflang, and routing decided deliberately.

  • Custom app development

    Private and custom apps against the Admin and Storefront APIs where an off-the-shelf app does not fit, including the webhook, retry, and alerting behaviour that makes an integration trustworthy.

  • ERP, PIM, and OMS integration

    Middleware or direct integration with the systems that hold the truth about inventory, pricing, and orders, built with reconciliation and failure alerting. Every integration ships with documented failure behaviour and an order and inventory reconciliation process.

  • Shopify Flow automation

    Operational automation for fraud review, tagging, inventory thresholds, B2B approval routing, and internal notifications, so that process lives in the platform rather than in somebody's calendar reminders.

  • Theme architecture

    A Liquid theme in version control with a documented branching model and a staging environment mirroring production. Sections, blocks, and a metafield and metaobject content model are structured so merchandisers can work without a developer.

  • Headless Hydrogen and Oxygen

    React-based storefronts on Shopify's own hosting, when the front-end requirement exceeds what Liquid can do, and a clear conversation about the merchandising and maintenance cost when it does not.

  • Performance, analytics and data layer

    Core Web Vitals work on the real bottlenecks, measured on field data: third-party scripts, image delivery, render-blocking resources, and app bloat, with an app stack audit and consolidation plan. A consistent event schema across GA4, server-side tagging, and ad platform conversions keeps the dashboards reconcilable.

First call

What you get on the first call

A short call is usually enough to tell whether your roadmap actually needs Plus.

Book a Strategy Call

  1. A read on whether Plus is the right answer

    Whether the capability you are paying for is the one that will move your revenue. If it isn't, we will say so.

  2. The Plus-only capability your roadmap depends on

    Which specific Plus-only capability your roadmap needs in the next twelve months, and what a lower plan already covers.

  3. Your integration landscape, looked at early

    We ask about your ERP, PIM, or OMS before quoting a timeline, and treat any system we have not seen as a discovery item.

  4. A scope that names its own unknowns

    The uncertain parts are named as uncertain, so the scope reflects what is actually known at that point.

Process

How a Shopify Plus build runs

  1. Step 01

    Technical discovery

    A structured audit of the theme and its customisations, the app stack, the integration landscape, the data layer, and the release process, plus the commercial context that determines what matters. The output is a scope that names its own unknowns.

  2. Step 02

    Architecture and design

    Decisions recorded with their trade-offs: Liquid or headless, single store or expansion stores, which logic belongs in Functions, where B2B sits, what integrates in real time. Interface design then runs against the real catalog and content, with states like out of stock, B2B pricing, and long product titles designed up front.

  3. Step 03

    Build and integration

    Two-week iterations in version control, with code review on anything touching checkout, pricing, or integrations, and a staging demo at the end of each. Systems are connected with reconciliation, retry, and alerting built in from the start.

  4. Step 04

    QA and launch

    Cross-browser and cross-device testing, accessibility review, load testing where traffic patterns justify it, and a full SEO parity check against the URL inventory and redirect map. Then a rehearsed cutover with a rollback plan, and deliberate monitoring of indexation, Core Web Vitals, and error rates in the days that follow.

  5. Step 05

    Post-launch and handover

    Technical documentation and a team walkthrough, platform maintenance, incremental feature work, and a conversion testing programme run on real behavioural data. The last of these is a different discipline from development and is scoped separately.

Plus vs. standard Shopify

What the Plus tier actually unlocks

Worth being precise about, because a good deal of what brands assume requires Plus does not. Upgrading to solve a problem a lower plan already solves is an expensive way to not fix it.

  • Checkout

    Shopify Plus
    Checkout UI Extensions and Shopify Functions; versioned, sandboxed, upgrade-safe
    Shopify (Basic / Grow / Advanced)
    Fixed checkout with limited configuration

  • Server-side logic

    Shopify Plus
    Functions for discounts, shipping, payment visibility, and cart transforms
    Shopify (Basic / Grow / Advanced)
    App-based or client-side scripts

  • B2B

    Shopify Plus
    Native company accounts, catalogs, price lists, and payment terms
    Shopify (Basic / Grow / Advanced)
    Apps, discount codes, or a separate store

  • Additional storefronts

    Shopify Plus
    Expansion stores included on the Plus contract
    Shopify (Basic / Grow / Advanced)
    Separate plans and separate billing

  • API limits

    Shopify Plus
    Substantially higher, making real-time integration practical
    Shopify (Basic / Grow / Advanced)
    Standard limits; batching required for heavy integration

  • Automation

    Shopify Plus
    Shopify Flow with a wider trigger and action set
    Shopify (Basic / Grow / Advanced)
    Limited automation; more manual process

  • Typical build cost

    Shopify Plus
    $50K to $250K depending on how much of the platform is used
    Shopify (Basic / Grow / Advanced)
    $15K to $50K for a custom theme build

  • Best suited to

    Shopify Plus
    Brands whose roadmap depends on a specific Plus-only capability
    Shopify (Basic / Grow / Advanced)
    Brands whose constraints are design, content, or marketing rather than platform
Why Conversion

How our Shopify Plus developers work

  • We will talk you out of the wrong build

    The most expensive Plus projects are the ones that solve a problem the brand did not have. If your constraint is merchandising, content, or acquisition rather than platform, a rebuild will not fix it, and we would rather say so at the scoping stage than eighteen weeks in.

  • Process before portfolio

    Version control, staging, code review, and a reversible deploy path are what make a Plus store maintainable. They are invisible in a case study and decisive in year two.

  • Integration treated as the hard part

    Front-end work is estimable. Integration is where Plus projects actually slip, so we scope it as discovery rather than as a fixed-price assumption about a system we have not seen.

  • Conversion literacy, not just delivery

    We build storefronts and we run conversion programmes, which means the build is informed by what actually changes behaviour rather than by what photographs well.

  • Honest about headless

    Hydrogen is a real capability and a real trade. We will recommend it when the front-end requirement justifies the operational cost and tell you when it does not.

  • Documentation as a deliverable

    A build you cannot hand to another team is not finished. Architecture decisions, integration behaviour, and release process are written down and walked through.

Questions

Shopify Plus development, answered

What does a Shopify Plus development agency actually do?
A Shopify Plus development agency builds and maintains stores on Shopify's enterprise plan, which means working with the parts of the platform that are not available on Basic, Grow, or Advanced. In practice that is checkout extensibility (Checkout UI Extensions, Shopify Functions, and branded one-page checkout), plus B2B on Shopify with company accounts and price lists, up to nine additional expansion stores on a single Plus contract, Shopify Flow automation, and higher API rate limits for integration work. A Plus development agency also owns the surrounding engineering: theme architecture, custom apps, ERP and PIM integrations, data layer and analytics, performance, accessibility, and the release process that keeps all of it deployable without breaking the storefront.
How is a Shopify Plus development agency different from a regular Shopify agency?
The difference is scope of platform access and scope of engineering risk. A standard Shopify agency works within themes, apps, and the Admin API, a large surface, but one where the checkout is fixed and the store is a single instance. A Plus agency works in a codebase where checkout is programmable, where Functions run server-side logic on discounts, shipping, payment, and cart transforms, where B2B and DTC can share one instance with different pricing and terms, and where an expansion store strategy introduces multi-store content and inventory decisions. That changes the discipline required: versioned deployments, staging environments, code review, and rollback plans stop being optional. Most stores that outgrow a standard agency outgrow it on process, not on design ability.
How much does Shopify Plus development cost?
Market ranges in the US and UK are roughly $50,000 to $250,000 for a full Shopify Plus build, depending on how much of the enterprise surface you actually use. A Plus build that is essentially a well-engineered theme with a few checkout extensions sits at the low end. A build with B2B company accounts, ERP-synced pricing, multiple Functions, several expansion stores, and a custom app sits at the high end. Headless Hydrogen builds typically start higher because you are taking on a front-end application in addition to the commerce layer. Separately, Shopify's own Plus platform fee is a licence cost paid to Shopify, not to your agency. See our Shopify Plus pricing guide for current published rates.
How long does a Shopify Plus build take?
A focused Plus build runs about 12 to 16 weeks. A build that includes B2B, ERP integration, custom Functions, and multiple markets runs 16 to 24 weeks. The variable that moves this most is not design or front-end engineering, it is integration. Getting clean, reliable data out of an ERP, PIM, or OMS is routinely the longest pole in the tent, and it is the part most likely to be underestimated at scoping. A credible Plus agency will ask to see your integration landscape before quoting a timeline, and will treat any system it has not seen as a discovery item rather than a fixed-price assumption.
Do I need Shopify Plus to get these features?
Some of them, yes. Checkout UI Extensions, Shopify Functions on checkout, B2B on Shopify, expansion stores, and the higher API limits are Plus-tier capabilities. But a large share of what brands assume requires Plus does not: custom theme architecture, most app integrations, a strong PDP and cart experience, subscriptions, internationalisation through Markets, and the vast majority of CRO work are all available on lower plans. It is worth being honest about this, because upgrading to Plus to solve a problem that a lower plan already solves is an expensive way to not fix the problem. If you are weighing the upgrade, the useful question is which specific Plus-only capability your roadmap depends on in the next twelve months.
What is checkout extensibility and why does it matter for development?
Checkout extensibility is Shopify's replacement for checkout.liquid. Rather than editing checkout markup directly, you extend checkout through Checkout UI Extensions (sandboxed components that render in defined slots) and through Shopify Functions, which run server-side logic for discounts, shipping methods, payment method visibility, and cart transforms. The practical consequence for development is significant: checkout customisations are now versioned, upgrade-safe, and reviewable, instead of being a fork of Shopify's own checkout that breaks on every platform update. Brands still running legacy checkout.liquid customisations are on borrowed time and should treat migration as a scheduled project rather than an emergency.
Can you work with our existing internal development team?
Yes, and on Plus builds it is common. The arrangements that work tend to have clear ownership boundaries: one team owns the theme and storefront, the other owns integrations or the internal systems those integrations touch, and both work from the same ticket tracker, the same staging environment, and the same definition of done. The arrangements that fail are usually the ones where ownership is shared without being defined, and two teams deploy to the same theme without a shared release process. We will ask about your branching model, your review process, and your deploy cadence early, because a mismatch there costs more than a mismatch in tooling.
What happens after launch?
Launch is when the actual data starts. A Plus store generates enough traffic that the questions you could only answer with judgement before launch become answerable with evidence after it: which checkout extension is helping, whether the B2B flow is being completed, where mobile is losing people. Post-launch work usually splits into three streams: stability and platform maintenance, incremental feature work, and conversion optimisation informed by real behaviour. The last of those is a different discipline from development, and is usually better run as a testing programme than as a backlog of changes someone felt strongly about.
Do you build headless Hydrogen storefronts on Plus?
Yes, when the case for it is real. Hydrogen and Oxygen make sense when you need front-end capabilities that Liquid genuinely cannot deliver: deeply custom interaction, a content model that outgrows the theme, or an app-like experience where the storefront is one of several consumers of the same commerce API. They make much less sense as a default, because going headless moves a large amount of previously-managed complexity onto your team: rendering, caching, preview, SEO, and the loss of the theme editor for merchandisers. The honest framing is that headless is a trade, not an upgrade. We will tell you when we think the trade is bad.
How do you handle B2B and DTC on the same store?
B2B on Shopify lets a single Plus instance serve both audiences: company accounts with multiple buyers and locations, per-company catalogs and price lists, payment terms, and quantity rules, all running against the same product data as the DTC storefront. The development work is mostly in the seams: theme logic that behaves differently for a logged-in B2B buyer, ERP-driven pricing that has to stay accurate, and a checkout that respects net terms. The alternative, running a separate wholesale store, is sometimes still the right answer when the two businesses genuinely share nothing but the catalog. That is a business-model question first and an architecture question second.
What does the discovery phase involve?
Discovery on a Plus build is mostly an inventory of what already exists and what constrains it. That means the current theme and its customisations, the app stack and which apps are load-bearing, the integration landscape and who owns each system, the analytics and data layer, the content model, and the release process. It also means the commercial context: which markets, which channels, which parts of the roadmap are committed. The output is a scope with the uncertain parts named as uncertain. A scope with no unknowns in it is not a more confident scope, it is a less honest one.
How do you protect SEO during a Shopify Plus rebuild?
By treating it as an engineering requirement rather than a post-launch checklist. That means a full crawl and URL inventory before anything changes, a redirect map built from that inventory rather than from assumptions, parity checks on titles, metadata, structured data, and internal linking, and a staged launch where indexation, Core Web Vitals, and Search Console coverage are monitored deliberately in the weeks after cutover rather than looked at when traffic drops. Most rebuild traffic losses are not mysterious. They are redirect maps that missed a template, or a change in internal linking that quietly orphaned a section of the catalog.
Pairs well with Shopify Plus development

Where a Plus build gets help

Shopify Plus development rarely runs in isolation. These are the adjacent areas it usually touches.

Book a call

Tell us what you are trying to build

A 30-minute call, a straight read on whether Plus is the right answer, and a scope that names its own unknowns.

What happens next

  1. 1Pick a time for a 30-minute call.
  2. 2Bring your integration landscape: the ERP, PIM, or OMS involved and who owns each system.
  3. 3Get a read on whether Plus is the right answer, and a scope that names its own unknowns.

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