Themes, apps, Functions, checkout and Hydrogen
Build scalable, secure online stores withprofessional Shopify development services
Most Shopify decisions come down to what your plan lets you change. We work out which customisations belong in the theme, in an app, in a Function or at checkout, and which ones need Shopify Plus, before anyone quotes for building them.
Shopify development work
Shopify runs the hosting and the platform. What remains for a developer is the storefront, the custom logic and the connections to your other systems.
Online Store 2.0 themes
Liquid themes where JSON templates act as wrappers for sections, so your staff can add, remove and reorder sections and blocks in the theme editor. We build the sections you need and keep logic in snippets, away from the merchant's settings.
Custom and public apps
New work goes on the GraphQL Admin API. Shopify made the REST Admin API legacy on 1 October 2024, and new public apps have had to be GraphQL-only since 1 April 2025. We also move older REST integrations across.
Integrations with your other systems
ERP, stock, accounting and fulfilment connections, written against a pinned API version. Shopify releases a new version every quarter and supports each for at least 12 months, so an integration needs a yearly upgrade slot in its plan.
Catalogue and data work
Products can now have up to 2,048 variants, up from the old limit of 100. Large catalogues still need thought about how options, metafields and collections are modelled, so that merchandising and filtering stay workable.
Shopify Functions, now that Scripts are gone
Shopify Scripts were deprecated on 30 June 2026, and any still published at that point were deactivated. Functions are the replacement, and they work differently.
What a Function is
A small WebAssembly program. Shopify passes it JSON shaped by a GraphQL input query, it returns JSON describing what Shopify should do, and Shopify calls it as needed during the customer journey. It is never called by URL, and we write them in Rust or JavaScript, the two languages Shopify supports first-party.
What they can change
Discounts, payment and delivery options, checkout validation, location rules, bundles, fulfilment constraints and local pickup. If a rule fits one of those, a Function is usually where it belongs.
The plan rule that catches people out
A store on any plan can use a public App Store app that contains Functions. Only Shopify Plus stores can use a custom app containing them, and some capabilities are Plus-only. So a rule written for one store may mean Plus, or finding an existing app.
Replacing old Scripts
If your discount or shipping logic stopped when Scripts were switched off, we start by listing what each script did. Then each rule goes to a public app, a custom Function, or a built-in Shopify discount, and we test the combinations that used to stack.
Checkout extensibility
checkout.liquid is no longer the way to change Shopify's checkout, so older stores may find that customisations have stopped working.
What has been switched off
checkout.liquid is unsupported on the Information, Shipping and Payment steps, and it was sunset on the Thank you and Order status pages on 28 August 2025. Script tags on those two pages ended on the same date for Plus stores and on 26 August 2026 for everyone else.
Checkout UI extensions
Extensions on the Information, Shipping and Payment steps are for Shopify Plus stores only. They run in an isolated sandbox with no access to the page's HTML or to payment details, and the compiled bundle cannot exceed 64 KB, which rules out some ways of building them.
Checkout Blocks
Shopify's own app. On Basic and higher, static and dynamic content blocks can go on the Thank you and Order status pages. Everything else in it needs Plus, so we check whether it covers your need before writing a custom extension.
Tracking after the change
Scripts that used to sit on the order pages need a new home, such as an app pixel or a custom pixel. Custom pixels run in a sandbox where not all pixel functionality works, so we test each conversion tag against your analytics rather than assuming it moved cleanly.
Shopify Plus, and when it is worth paying for
Shopify prices Plus by term and billing currency, on one-year or three-year terms. We compare what you need against what it adds, because it is sometimes unnecessary.
Checkout and custom logic
Extensions on the main checkout steps and custom apps containing Functions are the usual technical reasons to move. If a public app does the job, you may not need either.
Several stores
Plus allows 9 expansion stores, for different countries or separate physical locations, each needing its own theme licence if live. Organisation-level settings and analytics sit above them. We plan what is shared and what is duplicated before creating any.
B2B
Companies, net payment terms and up to 3 catalogues are available on lower plans. Unlimited catalogues and direct assignment of a catalogue to a company location are Plus-only, so the number of price lists you need often decides this.
Scale limits
Plus supports up to 200 locations, unlimited staff accounts and 20 million URL redirects, against 100,000 on other plans. Stores can also ask Shopify support for higher API rate limits, and Launchpad schedules promotions.
Hydrogen and headless Shopify
Hydrogen changed in its 2026-10 release. It is now a framework-agnostic library, rather than a framework tied to React Router, and that changes the advice for new builds.
Where a new storefront runs
Shopify ships two starters: React Router 7 deployed to Oxygen, Shopify's serverless hosting, and Next.js deployed to Vercel. Shopify says Oxygen is still free, and that a Hydrogen storefront can be hosted anywhere your framework can deploy.
Existing Hydrogen storefronts
Shopify says these keep working with nothing to do today. When you are ready, you can keep your pages and routes and change where the commerce code comes from. We would schedule that with other storefront work, not rush it.
What headless costs you
No Liquid theme means no theme editor for your staff, and apps that add features through a theme need another route. You also take on a front-end application to maintain. Checkout stays on Shopify, so it does not escape the rules above.
When we advise against it
If the goal is a faster store, we look at the current theme and its apps first. A headless build makes sense for a storefront a theme truly cannot express, or when you already run a web application and want Shopify commerce inside it.
Moving a store to Shopify
The data transfer is rarely the hard part. The risk is in search rankings, and in features your old platform did that Shopify does differently.
Import order
Products, then customers, then historical orders, so that orders connect to the right records. Shopify supports CSV import, migration apps and its APIs. We choose by volume, and by how much history you actually need to keep.
Redirects
Shopify's URLs will differ from your old platform's. A Shopify redirect only fires when the old address returns a 404, and prefixes such as /apps, /cart and /orders cannot be redirected, so we map old paths against those rules and check your most-visited pages after launch.
Payments
Shopify charges a plan-dependent transaction fee on orders through third-party gateways, and not on Shopify Payments. If you must keep your current gateway, that fee belongs in the comparison before you decide to move.
Features to rebuild or drop
We list every customisation on the old store and mark it as a theme change, an app, a Function or something to retire. That list usually matters more to the budget than the catalogue size.
When Shopify is the right choice, and when it is not
Shopify is a good default for many retailers, and a bad one for some. We would rather say so before you commit to it.
A good fit when
- You want hosting, security patches and platform upgrades to be someone else's job.
- Your store's differences are in brand and merchandising, more than in unusual order logic.
- Your custom rules fit Functions, or a public app already does them.
- You can use Shopify Payments, or the third-party gateway fee is acceptable.
A poor fit when
- You need to change the checkout's main steps but cannot justify Plus.
- Your process depends on code or data living on your own servers.
- Your pricing logic cannot be expressed through Functions and carts.
- You need full control of the URL structure at the platform level.
How Shopify projects run
The first step is deciding where each customisation lives, because that decides the plan and much of the price.
Audit or brief
For a live store, we review the theme, installed apps, any old Scripts or checkout code and the tracking. For a new one, we start from your catalogue and order rules.
Plan-aware scope
Each requirement is assigned to a theme, an app, a Function or an extension, and flagged if it needs Plus. You get this in writing with a price.
Build on a development store
Themes are developed with Shopify CLI on a separate theme, and apps and extensions on a development store, with test orders through each checkout path.
Launch and hand over
We publish outside your busy hours, check redirects, tags and order flow, then document the API version and the apps in use. Your team can take over, or we stay on.
Named projects and how we engage
No Shopify projects are named on this page. Most of our work is delivered under NDA, so many projects cannot be named.
Theme and app projects are quoted at a fixed price once we have seen the store or the brief. If you need developers working alongside your team, hourly work is from $20/h in USD, invoiced in USD, GBP, EUR or INR. We are an engineering team in India with 3–5 hours of overlap with the UK and Europe; US calls by appointment.
Shopify questions
Our Scripts stopped working. What do we do?
Shopify Scripts stopped running on 30 June 2026. Send us the old script code if you have it, or a description of the discounts and shipping rules it applied. We map each rule to a public app, a custom Function or a built-in discount. Custom apps containing Functions need Shopify Plus.
Do we need Shopify Plus to customise checkout?
For extensions on the Information, Shipping and Payment steps, yes. Stores on other plans can customise the look of checkout in the theme editor, and from Basic upwards can add static and dynamic content blocks to the Thank you and Order status pages through Checkout Blocks.
Should we build on Hydrogen?
Only if a theme genuinely cannot do what you need, or you already run a web application that should sell through Shopify. Since Hydrogen 2026-10 you can use it with Next.js or React Router, and host outside Oxygen. You lose the theme editor and take on an application to maintain, and checkout remains on Shopify.
Can you take over a Shopify theme and apps from another developer?
Yes. We start by listing the theme's customisations and every app, checking for code that relied on checkout.liquid or Scripts, and finding which API versions any integrations use. You get that list before we propose changes.
Will we lose search rankings if we move to Shopify?
Any platform move carries some risk, and no one can promise otherwise. Shopify's URLs will differ from your old ones, so we map every important page to a redirect, keep titles and content on the pages that bring in traffic, and check after launch that old addresses land where they should.
How much does Shopify development cost?
We quote after seeing the store or brief, because the plan and the number of custom rules drive the cost more than page count. Your Shopify subscription and any paid apps are separate, and are paid directly to Shopify and the app vendors.
Related services
Tell us about your Shopify store
Send your store's address, your plan and what you want changed. We will tell you where each change would live, and whether it needs Plus.
We reply within one business day (IST).