Shopify Plus agency or Shopify Plus developer? What Plus merchants need built

A Shopify Plus agency is the right choice when you need design, a theme build, development and often marketing from one team. But most of what makes Plus worth paying for is technical: checkout extensibility, Shopify Functions in custom apps, B2B, automation and integration with an ERP. That work is app development. You can hire a Shopify Plus development agency for it or a specialist Shopify Plus developer, as long as they know which features are really Plus-only and how to build them.

This page lists what Plus merchants actually need developers for, which features need the Plus plan, and how to choose who builds them.

What Shopify Plus unlocks for developers

Below are the Plus-only capabilities that most often drive development projects, as documented by Shopify.

That table decides a lot of architecture. For example, a custom discount rule for one Plus store can be a Function in a custom app. The same rule for a store on Advanced has to come from a public app, or be expressed with native discounts.

What Plus merchants actually hire developers for

Checkout extensibility

Checkout is customized with Checkout UI extensions, Functions and the branding API, not with checkout.liquid. checkout.liquid is no longer supported for the information, shipping and payment steps, and it was sunset on the Thank you and Order status pages on August 28, 2025. Typical Plus work includes:

• custom fields such as PO numbers, delivery instructions, gift messages and VAT or tax IDs, saved to order metafields;
• B2B-specific checkout content and validation;
• upsells, loyalty balances and trust content at specific checkout targets;
• address and cart validation that blocks bad orders before they are placed.

See Checkout UI extensions and checkout customization.

Shopify Functions, and the move off Scripts

Scripts stopped executing on June 30, 2026. Plus stores that had tiered pricing, gift-with-purchase, shipping-rate rules or payment method rules in Script Editor need them rebuilt as Functions, either in a custom app or with a public app. This is the most common Plus project in 2026. See Scripts to Functions migration.

B2B

Plus keeps the advanced parts of B2B on Shopify: unlimited catalogs, catalogs assigned directly to companies and locations, and partial payments and deposits. Developers connect this to the ERP, which holds company accounts, credit limits and contract prices, and build the ordering tools the native portal doesn't have. See Shopify B2B.

Launchpad and Flow automations

Launchpad schedules sales, product drops and restocks on Plus. Shopify Flow is available on every plan, but Plus stores can also use Flow tasks created by custom partner apps. Custom Flow triggers and actions from your own app are a clean way to let staff build automations on top of your integration, without new code for each rule.

Expansion stores

Many Plus merchants run more than one store: one per region, a wholesale store, an outlet. Developers handle product, inventory and customer sync between stores, shared apps deployed to each store, and consolidated reporting. If you are deciding between Markets in a single store and separate expansion stores, see Shopify-to-Shopify migration.

ERP and back-office integration

The biggest Plus merchants run NetSuite, Microsoft Dynamics 365, SAP, Acumatica or Odoo. Order, inventory, pricing and fulfillment sync is where connectors break most often. See Shopify ERP integration and NetSuite.

Shopify Plus agency vs Shopify Plus developer

The Shopify Plus Partner label is a program status for agencies, not a technical certification. Whoever you hire, the useful test is technical:

1. Ask them to tell you which of your requirements need Plus and which don't. Plan requirements change, and a good developer checks them rather than assuming.
2. Ask how they would test a Function and a checkout extension before it goes live.
3. Ask what happens when an integration fails at 2am: where does the error go, and how is it retried?
4. Ask what you own at the end: repository, hosting accounts, documentation.

What a typical Plus project looks like in 2026

A common shape: a Plus store that still had line item and shipping scripts, a checkout.liquid-era PO number field and an ERP connector struggling with B2B orders. The work becomes one custom app containing a discount Function and a delivery customization Function to replace the scripts, a Checkout UI extension for B2B fields backed by a validation Function, and a small integration service that syncs companies and catalogs from the ERP. Each piece is small. The value is in designing them together.

A checklist for Plus development projects

• List every customization that depends on Scripts, checkout.liquid, additional scripts or script tags, and its replacement.
• Confirm which requirements need Plus-only features, and whether each can be a public app instead of a custom app.
• Decide which system is the source of truth for products, inventory, prices and customers.
• Put config, such as thresholds, tiers and excluded products, in metafields so merchandisers can change it without a deploy.
• Test on a development store and on a copy of live data before launch, and roll out behind a flag where possible.
• Plan for quarterly API versions and platform deprecations after launch.