Desk fact
£15.4k
Replenhair cart + upsell revenue — no extra ad spend. UK Shopify store.
18 · Shopify Development
Shopify development agency for custom themes, store builds, and migrations that convert.
A Shopify development agency for custom theme development, store redesigns, app work, and WooCommerce or Magento migrations. We ship Online Store 2.0 stores that paid media can scale into — not a Dawn child theme with twenty apps.
Faster store. Cleaner cart. Higher conversion on the same traffic.
OS 2.0 themesStore & cartCustom appsUS-first · worldwide
- P&L desk
- Reply in one business day
- 30-min working session
Desk fact
+20%
Crossword additional revenue from a custom India-ready Shopify cart.
Desk fact
+649%
Lightspares gross sales in 6 months after catalog and store work.
Stores
Shopify stores on this desk
Logos from live Shopify merchants we build, customize, and grow — UK, India, Europe, and the US. Not a purchased logo wall.
Direct answer
What does a Shopify development agency do?
A Shopify development agency designs, builds, and maintains Shopify stores — custom theme development, store redesigns, apps, and migrations — so the storefront converts the traffic you already paid for. SpikeROAS is that desk with a P&L attached: Online Store 2.0 themes, cart and PDP work, and the pixels that paid media actually needs.
Most Shopify agencies ship a Dawn child theme, install a pile of apps, and call it a launch. Then the cart is a receipt, LCP is four seconds on mobile, CAPI is missing, and Google Shopping is bidding on a dirty feed. I built this desk because we kept inheriting stores that looked finished in a portfolio and died the week media scaled.
US work is the default: Shop Pay, sales tax, Merchant Center, and a feed Shopping can use. UK, Canada, India, and Australia get local wallets and tax when that is the brief — not a USD theme with a currency app. If you need Checkout Extensibility, Shopify Functions, or native B2B, that is Shopify Plus development — a separate page, because Google and the platform treat it as a different job.
Related: Shopify Plus development, ecommerce and DTC, CRO, performance marketing, and store and media results.
Sources: Shopify theme docs, Core Web Vitals, and Shopify Plus.
Fit
Who this Shopify development agency is for
Merchants who have outgrown a theme install and operators who need the store, the feed, and the ads on one scoreboard. If you only need a $2k Dawn skin, hire a freelancer.
DTC and catalog brands
Physical products on Shopify, enough media that a slow PDP actually hurts. Custom Shopify theme development and store redesign when the theme editor cannot express the brand — not because a deck said 'bespoke.'
Migrations and replatforms
WooCommerce, Magento, BigCommerce, or a custom stack that is expensive to keep alive. Products, customers, orders, and SEO redirects — not a pretty homepage with 404s behind it.
Stores that media cannot scale into
You are already buying Google and Meta. The leak is PDP, cart, or speed. That is a Shopify development job sitting next to CRO and paid — see ecommerce if the P&L is the brief.
Who we will not take
- Dropship lottery stores and 'I saw a theme on YouTube' briefs. We will say no on the call.
- Merchants who will not share margins, AOV, or the conversion number that has to move.
- Teams that want Hydrogen because it is fashionable. We pitch headless when Liquid cannot do the job.
- Agencies shopping for unpaid white-label theme labour with no access to the merchant.
The leak
What typical Shopify agencies get wrong
Theme-led, not conversion-led
Hero sliders, parallax, and a portfolio shot that tanks add-to-cart. We start from the funnel: collection → PDP → cart → checkout. Every section has to earn a metric or it does not ship.
App soup instead of engineering
Twenty apps for what Flow and a private app should do. Each app is a request, a discount conflict, and a future break. We cut what does not pay rent.
Speed treated as a post-launch ticket
LCP over two seconds on mobile is a tax on every ad dollar. We set a Core Web Vitals budget before sections ship. Theme awards do not pay the CPC.
One English theme, five markets
US Shop Pay, UK VAT, India COD, and AU Afterpay are not a currency toggle. We build the store for the market that is actually buying — starting with the United States when that is the auction you are in.
On the desk
Shopify development services on the desk
USA SERPs for 'Shopify development agency' split theme, custom, migration, and Plus into different jobs. We do the first three here. Plus is its own page.
Custom Shopify theme development
Online Store 2.0 sections and blocks your merchandising team can edit. Liquid done as software, not glued snippets. Mobile-first PDPs, collection filters, and a cart that sells a second item. Dawn is a starting point, not the product.
Shopify store setup and redesign
New stores and rebuilds of stores that look launched and leak. Catalog structure, navigation, PDP proof, and a cart drawer that is not a receipt. Redesign means conversion, not a new font.
Custom Shopify development
Private apps when the App Store cannot do the job. Cart drawers, bundles, subscriptions, ERP, 3PL, Klaviyo, and server-side CAPI. We already ship Shopify apps used on live merchant stores — this is not a first-time GraphQL project.
Shopify migration and replatforming
Catalog, customers, orders, URLs, and 301s from WooCommerce, Magento, or BigCommerce. SEO equity is a deliverable, not a hope. We cut over with a redirect map and a tracking checklist, not a 'we will fix rankings later.'
Shopify Plus development
Checkout Extensibility, Shopify Functions, native B2B, and Plus migrations live on a separate desk so this page does not pretend Plus is a theme upsell. If that is the brief, start with Shopify Plus development.
Performance, CRO, and the handoff to ads
LCP, INP, and CLS as a launch gate. Pixels, Enhanced Conversions, and CAPI in week one. Then conversion-rate optimization and performance marketing on the same desk so the rebuild is not an island.
Markets
Shopify development for US brands — and the markets they sell into
US Google results for 'Shopify development agency' are stores, themes, and migrations. Checkout tax and wallets still have to be local when you sell outside the US. We run one engineering OS. We do not paste a California theme into GST India and call it international.
Market
United States
Shop Pay, Shopify Payments, sales tax, and Merchant Center feeds that Shopping can actually use. Hardware-scale catalogs — we have run Google Ads on a Florida hardware brand to $2.65M at 3.91x ROAS, which only holds if the store and feed are honest.
Market
United Kingdom
VAT, Shopify Payments UK, Royal Mail, and Clearpay/Afterpay where the offer needs it. Replenhair is the UK proof: a cart and upsell system that added £15,451 without buying more clicks. Theme and checkout in GBP, not a USD store with a converter.
Market
Canada
GST/HST by province, Interac, Canada Post / Purolator, and bilingual storefronts when Quebec is in the brief. Markets and duties set correctly so a Toronto checkout is not a New York checkout with a maple sticker.
Market
India
GST invoices with HSN, Razorpay / UPI, COD with OTP, Shiprocket, and no-cost EMI. Crossword's custom cart had to carry Indian payment reality or it would have leaked. A US theme with a rupee symbol is not an India store.
Market
Australia
GST, Afterpay, Australia Post, and Shopify Payments AU. Theme and checkout built for AU mobile and AU shipping promises — not a US store that 'also ships to Sydney.'
The work
What we actually do
- Custom Shopify theme development on Online Store 2.0 — sections merchants can edit without breaking the build
- Shopify store setup and redesign: PDPs, collections, cart drawers, and a funnel that matches the ads
- Migrations from WooCommerce, Magento, and BigCommerce with redirects, customers, and orders intact
- Private apps, cart drawers, bundles, and ERP / 3PL / Klaviyo / CAPI integrations
- Performance budget: LCP, INP, CLS — Core Web Vitals as a launch gate, not a post-launch firefight
- US checkout, tax, Shop Pay, and Merchant Center feeds — plus local wallets when you sell UK, Canada, India, or Australia
Deliverables
You leave with
- Architecture and conversion brief (theme vs custom vs migration)
- Staging theme on your store, in your name
- Migration map: URLs, redirects, catalog, customers
- Launch checklist: pixels, CAPI, Shop Pay, speed
Ready to brief the Shopify Development desk?
Send the Shopify admin URL (or a staging preview) and the number that has to move. We will tell you what we would build — and what we would not.
Cadence
How the work runs
01
Audit the store, not the moodboard
Theme debt, app soup, cart leaks, and the number conversion has to move.
02
Build what the P&L needs
OS 2.0 theme, custom sections, or a migration — Plus work lives on the Shopify Plus development desk.
03
Launch and hand to media
Tracking live. Speed green. Then CRO and paid can actually scale.
First 90 days
First 90 days on a Shopify build
Days 1–14
Audit the live store
Theme, apps, cart, speed, tracking, and the conversion number. Kill list of apps and Liquid debt. Architecture call: OS 2.0, custom app, or migration. Plus checkout is a different brief. You get the plan before we write a section.
Days 15–45
Build on staging
Theme or checkout in your store, in your name. Catalog and redirect map if this is a migration. Weekly staging URL. No surprise 'big reveal' at week eight.
Days 46–75
QA, speed, and pixels
Core Web Vitals on real mobile. Shop Pay, local wallets, tax, and shipping. CAPI and Enhanced Conversions live so media is not blind at launch.
Days 76–90
Launch and hand to the P&L
Cutover, redirect QA, and a 30-day CRO + media plan. The store is not 'done.' It is ready to take traffic. If we are also the ads desk, week one of paid starts with a store that can convert.
The fork
SpikeROAS vs typical Shopify agency vs in-house
Hire us when the store has to convert paid traffic. Stay in-house when you already have Liquid engineers, a performance budget, and someone who owns the cart.
| Factor | SpikeROAS | Typical agency | In-house |
|---|---|---|---|
| Scoreboard | Conversion, AOV, LCP, contribution after the rebuild | Theme launch day and a Dribbble shot | Depends on whether engineering reports to marketing |
| Theme vs custom | Premium OS 2.0 when it is honest; custom when the UX cannot live in the editor | From-scratch Liquid to inflate the SOW | Usually a child theme that accretes debt |
| After launch | CRO and paid on the same desk | Maintenance retainer and a ticket queue | Roadmap fights with feature requests from every team |
| Plus work | A separate Shopify Plus development page — not stuffed into a theme quote | Plus logo on the website, Dawn under the hood | Thin unless you hired Plus engineers |
| Headless | Hydrogen when Liquid cannot; honesty when it can | Headless pitched to inflate the SOW | Often the right call if you already have React |
Pricing philosophy
No fake menu. An honest gate.
Shopify development is scoped as a build — theme, redesign, migration, or a cart system — not a fake $3k menu. US custom theme work typically sits in the mid-five-figures once catalog and apps are real. Theme customizations can be less. Plus checkout and Hydrogen are a different quote on the Plus desk. We will not bid a migration like a color swap.
- You own the theme, the apps, and the store. We do not hold the keys.
- Theme vs custom vs migration is an architecture call on day one, not an upsell at week six.
- Best with CRO and performance marketing so launch week has a readout.
- Shopify Plus platform fees are paid to Shopify. Plus engineering is quoted on the Plus page.
The call
What happens in 30 minutes
- 30 minutes. Working session on the live store — not a moodboard.
- Plan, AOV, the conversion leak, and whether this is a theme, a migration, or Plus.
- We will tell you what to build — or that a freelancer is enough.
Client result · United Kingdom
Shopify cart and checkout work for Replenhair.
A UK textured-hair brand had a cart that was a receipt. We replaced it with a Shopify cart drawer, product-page upsells, and a one-click post-purchase offer. Analytics from the live store: £15,451 total app-attributed revenue — £8,742 from the drawer, £4,136 from the product page, £2,573 after checkout. No extra media.
- Shopify cart drawer instead of a dead-end cart page
- Frequently-bought-together on the product page
- One-click post-purchase offer after payment — no second checkout
Total revenue
£15.4k
all placements
Cart drawer
£8.7k
57% of the total
Extra ads
£0
same traffic
Client result · India
Custom Shopify cart for Crossword Bookstores.
India's bookstore chain needed a cart that carried Express Checkout, gift cards, and no-cost EMI — not a stock drawer. We built the Shopify cart to Crossword's spec with a three-tier reward bar. The merchant reported a 20% lift in additional revenue. Store analytics: ₹340,639 from the drawer. Product-page and post-purchase still off.
- Custom Shopify cart drawer in Crossword's identity — not a templated app skin
- Three-tier reward bar: free shipping, then extra 5%, then extra 10%
- Express Checkout, gift cards, and no-cost EMI inside the drawer
Additional revenue
+20%
merchant baseline
Drawer revenue
₹340k
one placement
Extra ads
₹0
same traffic
FAQ
Questions we get about Shopify Development
What does a Shopify development agency do?
A Shopify development agency builds and maintains Shopify stores: custom themes, store redesigns, apps, integrations, and migrations. SpikeROAS also runs CRO and paid media on the same desk so the store is scored on conversion, not on whether the theme looked good in Figma.
How much does Shopify development cost?
US theme customization often sits in the high four to low five figures. Serious custom theme work usually starts in the mid-five-figures once catalog and apps are real. Freelancer theme installs can be a few thousand and usually look like it. We quote after seeing the store — not from a public menu.
How long does it take to build a Shopify store?
A focused OS 2.0 rebuild is often 6–10 weeks after discovery. A full migration can run a quarter. App-only work (cart, bundles) can ship in days. Anyone promising a custom store in a week is selling a theme with extra steps.
Do you offer Shopify Plus development?
Yes — on a separate page. Shopify Plus development is checkout extensibility, Functions, B2B, and Plus migrations. Stuffing Plus into a theme landing page is how agencies cannibalize both queries. If Plus is the job, start there.
Can you migrate from WooCommerce or Magento?
Yes. Products, customers, orders, and a redirect map so organic URLs do not 404. We treat SEO as part of the cutover. A homepage-only 'migration' that leaves your rankings on the old domain is not a migration.
Can you customize a theme or do you only build from scratch?
Both. We customize a premium OS 2.0 theme when it is the honest path, and we build custom when the brand or UX cannot be expressed in the theme editor. From-scratch is not a virtue. Conversion is.
Do you work on existing Shopify stores or only new ones?
Both. Most briefs are stores that already exist and leak: slow PDPs, a dead cart, dirty feeds, missing CAPI. We take over without a vanity replatform unless the theme is actually the bottleneck.
Do I need Hydrogen or headless Shopify?
Only if Liquid cannot deliver the UX, CMS, or performance you can measure. For most merchants, a fast Online Store 2.0 theme is cheaper to run and easier to merchandise. Headless on Plus is scoped on the Plus desk.
Do you work with US Shopify brands?
Yes. Shop Pay, US sales tax, and Merchant Center are the default. UK, Canada, India, and Australia are in the book when checkout and tax in that market are the brief. We will not launch a US theme into India and hope Razorpay 'just works.'
Do you run ads after the Shopify store launches?
Yes. That is why this desk sits next to performance marketing, CRO, and email. A rebuild that never sees a media plan is a brochure. We will not vanish at launch day unless you only hired development — and we will still wire tracking as if media is coming.
Usually paired with
Other desks on the same P&L
Shopify Plus Development
Shopify Plus development: Checkout Extensibility, Functions, B2B, and migrations — not a faster Dawn theme.
Conversion Rate Optimization
Make the traffic you already bought pay rent.
Landing Pages
The page is the second half of the ad.
Performance Marketing
Full-funnel paid that scales only when unit economics hold.
Industries
Where this service actually runs
Next step
If the store cannot take the traffic, stop buying more of it.
Send the Shopify admin URL (or a staging preview) and the number that has to move. We will tell you what we would build — and what we would not.