Shopify Plus agency: how to choose one for an enterprise build

You are shortlisting a Shopify Plus agency, and the proposals look alike: a polished theme, a list of apps, a launch date. The difference shows months later, when a checkout rule, an ERP sync or a wholesale price list meets real orders.

This guide turns what a Shopify Plus enterprise store build requires into questions you can ask on a first call. You will leave with a way to test any agency, the drivers that move budget and timeline, and the red flags worth catching before you sign.

It is written for e-commerce and operations managers who own the outcome: orders that flow, a team that stops re-keying data, and a store that does not need a rebuild in two years. Shopify hosts and secures the platform, so the agency's work starts where the platform's settings stop.

What a Shopify Plus agency delivers for you#

A Shopify Plus agency designs, builds and runs the parts of an enterprise store that the admin settings cannot do alone. That means custom checkout logic, back-office automation, several storefronts, wholesale selling, and the connections to your ERP (accounting and stock), OMS (order management), CRM (customer records) and PIM (product information). You get a store shaped around how your business sells, and a team that keeps it working after launch.

Shopify Plus is the plan. The agency is the engineering around it.

Plus build versus standard build#

A standard build installs a theme, configures products, shipping and taxes, and adds a few apps. Most of the work is configuration, and a capable freelancer can do it well.

A Plus build starts where configuration ends. The store has rules that differ by customer, region or order, data that lives in other systems, and traffic peaks that punish a slow page. Each of those becomes code, tests and an owner. For the background on what Shopify hosts and what stays yours to build, read how Shopify works: architecture, hosting and the SaaS model.

Signs your store is ready for Plus#

Plus is a plan, but the real question is whether your operation needs what it offers. These signs point to yes:

• Your checkout needs rules that standard settings cannot express, such as hiding a payment method for certain customers.
• You sell to businesses and consumers from one catalog, with different prices, terms and ordering rules.
• Several brands, regions or currencies need their own storefronts with shared operations.
• Your team re-keys orders, stock or customer data between systems every day.
• Campaign peaks create operational risk that a slow or fragile setup cannot absorb.

If two or three apply, a Plus conversation is worth having. If none do, a standard plan with a good agency may serve you better, and an honest agency will say so.

Plus features that need real engineering#

Five areas separate a Plus build from a standard one. In each, an agency has either shipped real work or is reading the documentation for the first time. The cards give you what you get and the proof to request.

Checkout extensibility and Shopify Functions#

Checkout is where revenue is won or lost, so it is where Plus engineering pays off most directly. The old checkout.liquid file has been replaced by checkout extensibility, which lets developers add to the checkout through supported extensions and settings instead of editing its code. Your checkout stays upgrade-safe, and Shopify keeps it fast and secure. Check the current limits in the Shopify developer docs before you approve a scope.

Shopify Functions are small pieces of custom logic that run inside Shopify at the moment of the order. They decide which discount applies, which delivery options appear, which payment methods show and whether a cart is valid. They replace many fragile scripts and apps with logic you own.

Ask to see a Function in production, who wrote its tests, and how it behaves with unusual input, such as an empty cart or a customer holding two discounts. An agency that has shipped one answers in specifics.

Shopify Flow for back-office automation#

Shopify Flow is a built-in automation tool: when something happens (a trigger) and a condition is true, an action runs. It can tag high-value customers, hold an order that looks risky, alert the warehouse about low stock or call an outside system. Your team gets hours back without another app.

The skill is design, not clicking. Ask the agency to walk you through a Flow map from a live store: triggers, conditions, owners and what happens when an action fails. Workflows that nobody documents become the next mystery in your store.

Multi-store and expansion stores#

Plus allows additional stores for separate brands, regions or wholesale. Each has its own catalog, theme and settings. The cost is that every extra store multiplies theme releases, product data and inventory sync.

A strong agency first asks whether one store with Shopify Markets (regional currencies, languages and domains) is enough. Separate stores make sense when brands, legal entities or catalogs truly differ. Ask, "When would you advise me to keep one store?" An agency that always recommends more stores is selling more work.

B2B on Shopify: companies, price lists, terms#

On Plus, Shopify models a wholesale buyer as a company with locations, catalogs, price lists, payment terms and quantity rules. You get a wholesale experience inside the same store your retail customers use, not a second system to maintain.

The engineering sits in the edges: a customer with three locations and different terms, prices that come from your ERP, an order that needs approval. Ask how the agency would model your most complicated account. Its first question should be about your data, not your theme.

Theme architecture and performance budgets#

A Plus store carries a large catalog, frequent merchandising changes and heavy campaign traffic. The theme must stay easy to edit and fast when all three arrive. Both qualities come from decisions made before design starts.

Liquid sections, blocks and a maintainable theme#

Liquid is Shopify's templating language. Modern themes are built from sections and blocks that your marketing team arranges in the theme editor without a developer. A well-structured theme keeps product data in metafields (custom fields), reuses components, and lives in version control with a staging theme for testing.

The result is practical: a campaign page ships in hours, and a developer's change does not break the homepage. The post on how the Liquid theme system builds scalable stores goes deeper. Ask the agency to show its repository structure and its deployment routine.

Setting a Core Web Vitals budget before design#

A performance budget is a limit, agreed up front, on how heavy and slow a page may become. Google documents three "good" thresholds, measured at the 75th percentile of real visits: LCP under 2.5 seconds (how fast the main content appears), INP under 200 milliseconds (how fast the page answers a tap) and CLS under 0.1 (how little the layout jumps). Use them as the starting budget for your home, collection and product pages.

The agency should say how it measures (real visitor data, not only lab tests), who watches the numbers after launch and what happens when a new app or banner pushes a page over budget. A budget that nobody monitors is a wish.

Apps versus custom code decisions#

Apps are quick to install and carry costs: monthly fees, scripts that load on every page and data that lives with a third party. Custom code takes longer up front, has no monthly fee and loads only what you need. The post on the Shopify app ecosystem, its limits and hidden costs covers the trade-off in detail.

A fair rule: use an app for commodity features such as reviews, and custom code for logic that is core to how you sell, such as pricing rules, B2B ordering and checkout. Ask for an app inventory in the proposal with each app's purpose, monthly cost, effect on speed and a plan to remove it.

Integration load: ERP, OMS, CRM and PIM#

In many Plus projects, integrations take more effort than the storefront. Stock lives in one system, prices in another and customers in a third, each with its own rules and quirks. The store is where all of them meet a shopper.

Follow one order through the stack and you see where the engineering sits. The visitor lands on the theme, checkout applies your Functions, Flow reacts to the new order, the OMS and ERP receive it, and the CRM and PIM stay in step.

Order journey

1. 01Storefront themeVisitor lands and builds a cart
2. 02Checkout and FunctionsCustom rules apply to the order
3. 03Flow triggersNew order starts automated actions
4. 04OMS and ERPWebhook sends the order onward
5. 05CRM and PIM syncCustomer and product data stay aligned

Order journey through a Shopify Plus store, from the theme to checkout, Flow, OMS and ERP, then CRM and PIM sync

Map systems, owners and sync direction#

Before anyone quotes, write one page: for each type of data, which system is the source of truth, which way it moves, what triggers it and who owns it. This turns a vague "we need ERP integration" into a list an agency can estimate. For example (illustrative), a store with an ERP, OMS, CRM and PIM might map like this:

Five rows become at least seven separate flows, and each one needs an owner and a plan for when it fails. That is why two quotes for "the same store" can differ so much.

Webhooks, queues and error handling#

A webhook is a message Shopify sends to another system the moment something happens, such as a new order. A queue holds those messages, so when your ERP is slow or offline at 2 a.m. during a sale, no order is lost. Good integrations also retry failed messages, ignore duplicates so one order is never booked twice, and alert a person when something needs attention.

Ask, "What happens if our ERP is offline during a sale?" A prepared agency answers with queues, retries and alerts. The integrations service page shows how werun.dev approaches this work.

What to ask about past integrations#

Past projects are the best evidence. Ask the agency to describe:

• Which ERP, OMS, CRM or PIM it has connected, and what went wrong the first time.
• Where the integration code runs, who owns that hosting and who pays for it.
• How failures are monitored, and who gets the alert.
• One incident, what caused it and what the team changed afterwards.
• What documentation you receive at handover.

Shopify Plus agency cost and timeline#

Shopify Plus agency cost depends on scope, not on a standard rate. An agency that names a final price before discovery is guessing. This section gives you the drivers, so you can compare quotes on the same basis, and no market prices, because they would age quickly and mislead you.

Migration: what moves and what gets rebuilt#

A migration moves products, customers, order history, content and URLs from your current platform. The data moves through a mapping exercise. The theme and the checkout logic are rebuilt, because other platforms store them differently, and every customization that lived in a plugin needs a new home as a Function, a Flow or an app.

Two details protect you. A redirect map keeps your search traffic when URLs change, and a decision on order history (import it or keep an archive) avoids a late surprise. Customers often need to set a new password, so plan that message. A good Shopify Plus migration agency lists all of this in the proposal.

New build: where the time goes#

In a new build, time goes to decisions more than to code: how products are structured, which rules live in checkout, which systems feed the store. The theme is usually the quicker part. The risk is scope growth, because new ideas arrive once the team can see the store.

What moves a quote up or down#

These are the levers that change a quote the most. Ask each agency how it priced every one:

• The number of systems to integrate and the quality of their data.
• The number of custom checkout rules and Functions.
• Storefronts, markets and languages.
• B2B complexity: companies, price lists, approvals.
• Custom design versus an adapted theme.
• How quickly your team can review and approve.

For example (illustrative), picture two stores with the same visual design. Store A has one storefront, standard checkout and an order sync to one system. Store B has two storefronts, four connected systems, three Functions and wholesale accounts. The pages look alike, but Store B holds far more engineering, and its quote should show that.

The phases below show how an enterprise build typically unfolds. Their length depends on the levers above.

1. Phase 1

   Discovery

   Goals, the system map and the performance budget are agreed in writing.

2. Phase 2

   Architecture and integration design

   Theme structure, checkout rules and sync directions are designed before building.

3. Phase 3

   Build

   Theme, extensions, Functions, Flow and integrations are developed on a staging store.

4. Phase 4

   QA and data migration

   Real orders, edge cases and imported data are tested end to end.

5. Phase 5

   Launch and hypercare

   The team watches orders, speed and syncs closely in the first days after go-live.

Budget for the last phase too. Launch is the start of real traffic, and the first weeks show what testing could not.

Questions to ask a Shopify Plus agency#

Each question below tests one requirement from this guide. A strong answer names a project, a tool and a trade-off. A weak answer repeats the brochure.

Eight questions for the first call#

Take these to every call, and compare the answers side by side. Notes written the same day beat memory a week later.

• Which Shopify Functions and checkout extensions have you shipped, and how do they behave in production?
• What performance budget will we agree before design, and who monitors it after launch?
• Which ERP, OMS, CRM or PIM have you connected, and how do you handle failed syncs?
• How would you model our most complex B2B account?
• When would you advise one store instead of several?
• Who owns the code, the repositories and the accounts at handover?
• What response time do we get after launch, and who answers?
• Can we speak with a client whose store has been live for over a year?

Listen for specifics. "We built a Function that validates minimum order quantities by customer group, and here is how we tested it" is a strong answer. "We have a lot of Plus experience" is not an answer yet.

Red flags in proposals#

These patterns are worth a second conversation before you sign:

• A fixed price with no discovery phase and no system map.
• A long list of apps for logic that Functions or Flow could handle.
• No performance budget, or one described only as "we optimize speed".
• Code or hosting that the agency owns and you cannot take with you.
• No named person for support after launch.
• Plus recommended for every case, including stores that do not need it.

None of these proves bad intent. Each one tells you where to push for clarity.

How to check references and code ownership#

Ask for two references: one recent launch and one store live for a year or more. The older one tells you how the agency behaves once the excitement is over. Ask that client how quickly issues were fixed and whether the agency flagged problems before they did.

For code ownership, ask for three things in the contract: repositories in your organization, collaborator access to your store under your account, and documentation of every integration and where it runs. If you ever change agency, these decide whether the move takes days or months.

How werun.dev runs your Plus store after launch#

Launch day is the beginning of the work for us. You set the goal, whether that is more wholesale orders, a faster checkout or fewer manual hours, and we stay beside you while the store earns it. We have looked after 200+ sites over 12+ years, and the habits that make that possible apply to Plus stores too.

Care plan and Retainer: who does what#

The monthly Care plan covers maintenance: keeping the theme, apps and integrations healthy, watching for problems and fixing what breaks. The monthly Retainer gives you a steady block of build time for improvements, such as a new Function, a new market or a new B2B rule. One keeps the store safe, the other moves it forward, and many teams use both.

We reply in under 2 hours on business days, so a stuck order sync or a checkout question does not wait overnight. Put the response time in writing with any agency you hire, including us.

Changes, experiments and the monthly report#

Changes start with Client Feedback: your team clicks anything on the site and asks for a change, so requests arrive with the exact element attached. Requests, projects and invoices live in the client panel, and nothing hides in an email thread.

Before a big change goes live to everyone, werun.Experiments can test it with real visitors, so a winner is picked by results, not by opinion. A written monthly report then tells you what we changed, how speed and orders moved and what we suggest next. You see the work, and you decide the direction.

Where to start this week#

One page will improve every conversation you have with an agency. Write down each system your store touches (ERP, OMS, CRM, PIM, shipping, payments), who owns it, and which way data moves. Add one sentence with your goal, such as "wholesale buyers reorder online without calling sales".

Send that page to the agencies on your shortlist and compare how they respond. If you would like us in that comparison, tell us your goal through the contact page and we will reply within 2 hours on business days. You can also see how we work on the Shopify platform page.

Frequently asked questions#