What A Shopify Development Agency Should Actually Know

How Should You Judge A Shopify Development Agency?

Judge a Shopify agency on where they put the logic, not on what the store looks like.

Shopify now has several distinct places custom behaviour can live. The theme. An app. A Function running on Shopify's own backend. A checkout extension. Each has different limits and a different maintenance profile. Picking the wrong one is the expensive mistake, and it is invisible in a portfolio.

That is my test, formed from doing the work rather than from any Shopify document. The version question below is the part you can check for yourself.

The Platform Moves Every Quarter

This is the bit merchants are rarely told up front.

Shopify's own documentation states that it releases a new API version every three months, at the beginning of the quarter, at 5pm UTC. Each stable version is supported for a minimum of twelve months, with at least nine months of overlap between consecutive versions.

At the time of writing, version 2026-07 was released on 1 July 2026 and is accessible until 16 July 2027. The next, 2026-10, arrives on 1 October 2026.

So a build that calls those APIs is never finished in the way a brochure site is finished. It has a supported window. Nine months of overlap is generous, and it is also a deadline.

The practical consequence is a question worth asking before you sign anything. Which version is this built against, and who moves it forward.

Where The Work Actually Lives Now

Four places, and they are not interchangeable.

The Theme. In practice, presentation and storefront rendering. Online Store 2.0 brought sections to every page, and Shopify's own migration guidance is clear that upgrading is not mandatory, and that merchants can continue using a vintage theme if it meets their needs. That is worth reading before anyone sells you a rebuild.

Shopify Functions. These customise the backend logic of Shopify itself. They cover discounts, payment and delivery options, checkout validation, order routing, product bundling, fulfilment strategies and local pickup. They run on Shopify's infrastructure and are never invoked directly by URL, since Shopify calls them as needed within the customer journey.

Checkout. Shopify's changelog describes checkout extensibility as a set of pieces: checkout UI extensions and Functions for new functionality, the Checkout Branding API for styling, and Pixels for event tracking. More in Checkout Extensibility, And What Already Broke.

Apps. My rule of thumb is that anything needing to run outside the store, hold its own data, or be installed by more than one merchant belongs here.

Two more areas sit alongside those. Store Optimisation covers the storefront work that affects revenue without extending the platform. Migration And Replatforming covers getting onto Shopify at all.

Six areas in total. Most briefs I see touch two or three of them without realising it, which is usually where the scope creep comes from. The Shopify Services are set out on the main site.

Functions Are The Part Most Briefs Get Wrong

Worth singling out, because in my experience it is the layer briefs most often place wrongly.

Functions must compile to WebAssembly. Shopify provides templates and client libraries for Rust and JavaScript, and its documentation strongly recommends Rust as the most performant choice, to avoid the function failing with large carts.

That last detail matters commercially. A discount rule that works in testing can fail on a big basket if the wrong language was chosen. It is not a design preference, it is a documented failure mode.

The area is also actively developed. Shopify's changelog entry of 30 July 2026 records that createdAt is now available on the Customer object in Functions. That is the kind of change that quietly widens what is possible between one quarter and the next.

If you already know your store needs custom backend logic, The Free Store Audit is a reasonable place to start.

Signs You Need Shopify Development, Not Configuration

Five signals, drawn from the briefs that come across my desk. The more you recognise, the more likely you need development rather than configuration.

1. You are paying for three or more apps that each do a fraction of one job, and they conflict.
2. Someone has edited theme code to change how pricing or shipping behaves. That logic is in the wrong place.
3. Your team exports a CSV, changes it, and imports it again on a schedule.
4. You have been told a change is impossible, without being told which layer it was impossible in.
5. Nobody can tell you which API version your existing customisations were built against.

The last one is the fastest to check and the most revealing.

Common Questions About Shopify Development

What Does A Shopify Development Agency Do?

It builds what the platform does not provide by default. In practice that means theme work, apps, backend logic through Functions, checkout extensions, and migrations from other platforms. In my view the line against a design studio is that logic and data are involved, not only layout, which is what brings a maintenance window with it.

How Often Does Shopify Change?

Shopify releases a new API version every three months, at the beginning of the quarter, at 5pm UTC. Each stable version is supported for a minimum of twelve months, with at least nine months of overlap between consecutive versions. Smaller changes land continuously and are published on the Shopify developer changelog.

Is Upgrading To Online Store 2.0 Mandatory?

No. Shopify's own migration assessment states that upgrading to Online Store 2.0 is not mandatory, and that merchants can continue using a vintage theme if it meets their needs. It sets out four paths, including staying put. Treat a rebuild as a decision to justify, not a default.

What Language Are Shopify Functions Written In?

They must compile to WebAssembly. Shopify provides function templates and client libraries for Rust and JavaScript, and strongly recommends Rust as the most performant choice, to avoid your function failing with large carts. That recommendation is a performance constraint, not a stylistic preference.

What Is Checkout Extensibility Made Of?

Shopify's developer changelog describes it as checkout UI extensions and Shopify Functions to surface new functionality, the Checkout Branding API to customise styling, and Pixels to track events. The entry announcing it was published on 28 June 2022, when the feature was in developer preview.