Top Shopify Theme Design, Development And Custom App Agencies
Daria Pohrebniak
Marketing Director - Reverb
07.07.2025
This list covers the top Shopify theme design, development and custom app agencies, for merchants who want a custom storefront, a reworked theme or bespoke Shopify functionality.
When it comes to building a successful Shopify store, your theme can make or break the customer experience. From clean design to seamless functionality, the right agency can help you create a storefront that not only looks great but also drives conversions.
In this article, we highlight the top Shopify theme design agencies that specialize in crafting custom themes and solutions tailored to your brand. Whether you’re launching your first store or scaling to Shopify Plus, these experts combine creativity and technical skill to help your business stand out in the crowded eCommerce landscape.
Shopify Theme Development Agencies At A Glance
This table summarizes each agency’s location, services and team size as stated in its entry below.
1. Agency
Location
Services
Team size
1. Realm
United States
Store setup and migrations, Shopify POS, custom themes, app development
2-10
2. Avex
New York, US
Shopify Plus migrations, UX/UI design systems, headless commerce
11-50
3. WebDesk Solution
Toronto, Canada; Great Neck, New York, US
Ecommerce consulting, Shopify and BigCommerce migrations, custom development
8-20
4. Evestar
United States
Shopify and Shopify Plus development, custom themes and apps, migrations, CRO
50-249
5. Swanky
Exeter, UK; offices in Australia and France
Shopify Plus migrations, custom themes and apps, headless commerce
50-200
6. Electric Eye
Ohio, US
Custom themes and apps, migrations, optimization
2-10
7. Diff Agency
Montreal (HQ); San Francisco; Toronto
Custom Shopify Plus themes and apps, UX/UI, headless commerce
100-150
8. The Working Party
Hawthorn, Victoria, Australia
Shopify Plus design and development, migrations, growth programs
11-50
9. Underwaterpistol
London, UK
Shopify Plus design and development, custom apps, theme design, UX/UI
11-50
10. Arctic Grey
Silicon Valley (HQ); offices in the US, Canada and London
Custom Shopify Plus themes and apps, enterprise migrations
80+
11. Charle
London, UK
Shopify and Shopify Plus design and development, migrations, UX/UI
11-50
Best Shopify Theme Design and Development Agencies
Realm is a full-service Shopify agency started by one of Shopify’s first experts. Since 2012, they have built successful stores for Fortune 500s, start-ups and Shopify Plus. They’re known for their Shopify expertise, pixel perfect aesthetics and an in-depth understating of visitor’s shopping experience. Because of their proven track record of increasing sales, ROAS and delivering the best ROI for their clients, they are one of the most sought-after Shopify agencies.
Realm has worked with over 250+ brands and have established an impressive reputation with countless 5-star reviews. When you work with Realm, you can expect top-notch service and a dedication to the success of your brand backed by support for the years to come.
Services and expertise: Shopify store set‑up & migrations, Shopify POS, custom theme design, app development, Shopify SEO, content writing, digital marketing (Facebook, Instagram, Email/SMS, Google), Shopify Plus enterprise, conversion optimization and ongoing support.
Team size: 2-10 employees
Location: headquartered in the United States, operating globally
Clients: SYLTBAR, Byers’ Choice LTD, Lash & Wax OC, Freewaters, zkano, CoolSnowGlobes, Sunrise Flour Mill and more.
Avex is an award‑winning Shopify Plus agency delivering unified commerce experiences for enterprise and high-growth brands. With over a decade of industry leadership, their strategic, design-first approach spans DTC, B2B, and retail, combining UX/UI design, headless commerce, CRO, and email/SMS marketing to provide the best Shopify app development services.
Their team is known for attentive collaboration, thoughtful problem-solving, and delivering outcomes that resonate with both brands and their customers. By bridging creative vision and technical execution, Avex supports brands in building meaningful connections and driving long-term success online.
WebDesk Solution is a North American digital agency turning eCommerce goals into reality with expert design, development, and AI-driven innovation. With 13+ years of experience and 500+ clients, they craft tailored platforms, from headless commerce to web and mobile apps focused on speed, UX, and seamless integrations. Recognized as one of the best Shopify design agencies, they’re certified partners with Shopify and BigCommerce, delivering high-performance solutions through agile processes and thorough discovery.
Known for award-winning designs and attentive post-launch care, WebDesk helps brands stay competitive with data-driven strategies, advanced conversion tracking, and measurable growth in fast-changing markets.
Evestar is a North American agency that is among the top Shopify theme design agencies. Founded by entrepreneur Lolita Petrossov, the team applies design‑focused and data‑driven strategies across creative, development, and marketing disciplines. They have supported over 200 brands in increasing revenue and conversion rates through thoughtful optimization and testing.
Clients report significant improvements, such as doubling online revenue within months and achieving 600–700% ROAS on campaigns. Known for collaborative workflows and attention to detail, Evestar helps brands make informed decisions and strengthen their digital presence in a competitive eCommerce landscape.
Services and expertise: Shopify & Shopify Plus development, custom theme and app builds, migrations, CRO, performance marketing (Facebook/Google/TikTok, email/SMS automation), SEO, UI/UX, paid social creative, headless solutions
Team size: 50-249 employees
Location: headquartered in the United States, operating globally
Swanky is a full-service Shopify Plus agency operating across the UK, Australia, and France. Since 2010, they’ve focused exclusively on Shopify, earning “Shopify Plus Expert” accreditation in 2016 and achieving Platinum Partner status in 2025. Their team blends design, development, data analysis, and strategy to tackle complex eCommerce challenges like subscription models, international expansion, and composable commerce setups.
Trusted by mid-market and enterprise brands, Swanky emphasizes a test-and-learn approach, reportedly achieving up to 60% CRO win rates and supports long-term growth through continuous optimisation and full-funnel marketing.
Services and expertise: Shopify Plus migrations, custom theme & app development, composable & headless commerce, conversion rate optimisation (CRO), analytics, subscription site builds, digital marketing, internationalisation
Team size: 50-200 employees
Location: Exeter (UK), offices in Australia & France, serving global clients
Electric Eye, founded in 2016 in Columbus, Ohio, provides custom Shopify theme development and optimization for direct-to-consumer lifestyle brands. With over 100 Shopify stores delivered, their team focuses on mobile-first design, speed improvements, UX/UI enhancements, and conversions through diagnostics, A/B testing, and landing page optimization.
Clients highlight Electric Eye’s clear communication, reliability, and ability to simplify complex migrations and technical challenges. By combining data-informed insights with a consultative approach, they support brands in building polished, performant storefronts that resonate with customers and reduce operational friction.
Services and expertise: Custom Shopify theme & app development, migrations (Matrixify experts), optimization & maintenance retainers, diagnostics, UX/UI, CRO, page speed, landing pages, A/B and user testing, eCommerce strategy
Diff Agency is a full-service commerce consultancy and Shopify Plus Partner known for engineering high-performance online stores. With a track record of over 15 major brands, they deliver tailored solutions spanning custom theme development, app integration, and UX optimization.
Their collaborative, data-led approach shows results like a 430% sales increase for a DTC bedding brand and significant operational savings for Canadian fashion retailer Rudsak, where they helped save over 5,410 hours annually. Diff also hosts industry events such as “Constructing CX” in partnership with Shopify to explore advanced customer-experience systems.
Services and expertise: Custom Shopify Plus theme & app development, UX/UI design, integration & headless commerce, conversion optimisation, QA, digital analytics, omnichannel strategy
Team size: 100-150 employees
Location: headquarters in Montreal, with additional operations in San Francisco and Toronto
Clients: Tommy John, Fashion Nova, PopSockets, Boll & Branch, Rudsak, Tonies, Lionsgate, Bouclair, Sakara, Hill’s Pet Nutrition
Founded in 2011, The Working Party has become one of the best Shopify design and development agencies. They’ve led Shopify Plus launches for major retailers like JB Hi‑Fi, KOOKAÏ, Assembly Label, Lovisa, and New Era, applying their proprietary Growth Framework to deliver design-driven, data-led eCommerce solutions.
Leveraging retail-industry insights, the agency manages full lifecycle projects, including migrations from platforms like Magento, Salesforce, and Hybris while supporting ongoing optimization and international growth. Their disciplined, client-focused approach underpins successful case studies where brands continue to evolve post-launch.
Services and expertise: Shopify Plus design & development, migrations, growth framework (CX, SEO, performance, analytics), integrations, composable/headless commerce, internationalisation, subscription/omnichannel strategy
Team size: 11-50 employees
Location: Hawthorn, Victoria, Australia (offices in Melbourne and Sydney)
Clients: JB Hi‑Fi, KOOKAÏ, Assembly Label, Lovisa, New Era, Mister Zimi, Sheike, Farmers Pick, Deus ex Machina, CSD Brands
Underwaterpistol is a UK-based Shopify Plus agency operating from London since 2003. With over two decades of experience, they’ve completed more than 200 projects in-house across industries like fashion, food and drink, and home goods. Their in-house team covers everything from creative design to technical development, with a structured four‑phase framework focused on planning, building, growing, and accelerating eCommerce success.
Known for a test-driven, data-led approach, Underwaterpistol has delivered outcomes such as improved customer loyalty tools and smoother platform migrations for clients. Recognised by many as a best Shopify app development company, they’re valued for solving complex eCommerce challenges through integrations, customised apps, and ongoing optimisation support.
Services and expertise: Shopify Plus design & development, custom app development, theme design, UX/UI, subscriptions & loyalty programs, SEO, CRO, platform migrations, internationalisation, analytics & optimisation
Team size: 11-50 employees
Location: headquartered in London, operating globally
Arctic Grey is an award‑winning Shopify Plus agency that supports enterprise-level merchants across North America and Europe. They’ve worked on over 1,000 Shopify stores, helping generate upwards of $1.5 billion in client revenue and earning more than 550 five‑star reviews and 28 commerce awards. Their team blends design, development, and performance optimisation, specialising in mobile-first UX, custom theme work, migrations, and speed improvements.
Through data-led work such as a 30% lift in conversion within one month for a jewellery retailer and a 22% increase for a beauty brand, Arctic Grey demonstrates measurable impact . Their structured, full‑lifecycle approach aims to support long-term ecommerce growth while keeping stores stable and scalable.
Charle is a London-based Shopify and Shopify Plus agency delivering high-performance ecommerce experiences for ambitious growth brands. With a search-first, performance-led approach, they combine UX/UI design, technical development, SEO, and CRO to build stores that are engineered not just to look good, but to scale revenue. Their work spans DTC, lifestyle, beauty, and retail brands, blending creative direction with deep Shopify expertise to drive measurable growth.
Their team is known for strategic thinking, transparent collaboration, and long-term partnership rather than one-off builds. By aligning technical execution with data insights and search intent, Charle helps brands launch, migrate, and optimise Shopify stores that perform across acquisition, conversion, and retention. They bridge design, engineering, and growth marketing into a unified ecommerce strategy built for sustainable results.
Services and expertise: Shopify & Shopify Plus design and development, Shopify migrations, UX/UI optimisation, technical SEO, CRO & A/B testing, performance marketing support, ongoing retainers
Team size: 11–50 employees
Location: Headquartered in London, United Kingdom
Clients: Fast-growing UK and international ecommerce brands across fashion, beauty, lifestyle, and retail
What Shopify Theme Development And Customization Include
Shopify theme work ranges from light adjustments to a fully custom storefront. Most projects fall into one of three levels:
Theme customization: starting from a Shopify theme and adjusting layout, sections, typography, colors and templates to fit the brand.
Custom theme development: designing and building a theme from scratch in Liquid, often with a design system, custom sections and blocks that the store team can edit without code.
Headless builds: separating the storefront from Shopify’s back end using Hydrogen or another framework, for brands that need maximum control over performance and experience.
A full theme project usually includes discovery and UX research, wireframes and visual design, front-end development, app and third-party integrations, speed and accessibility work, testing across devices, data migration if you are moving platforms, and training for the store team. Custom apps are a separate layer: they add functionality, such as subscriptions, product configurators or ERP connections, that a theme alone cannot provide.
How To Choose A Shopify Theme Development Company
Review live stores the agency has built, and test them on mobile for speed and usability.
Decide how custom you need to go. A customized theme is faster and cheaper; a custom build suits brands with specific UX or performance requirements.
Check Shopify Plus and migration experience if you are a larger merchant or moving from another platform.
Ask how the theme will be edited later. Well-built sections let your team change content without a developer.
Confirm app and integration skills if you need custom functionality.
Clarify post-launch support and who owns the code.
Should you customize a Shopify theme or build a custom one?
Customizing an existing theme is usually the right choice for newer or smaller stores because it is faster, cheaper and easier to maintain. A custom theme makes sense when your brand needs a distinctive experience, complex merchandising or performance that an off-the-shelf theme cannot deliver.
How do Shopify theme development agencies charge?
Most agencies quote a fixed project fee after discovery, based on the number of templates, custom sections, integrations and whether a migration is involved. Smaller changes are often billed hourly, and many agencies offer monthly retainers for ongoing development, optimization and support.
What is the difference between a Shopify theme and a Shopify app?
A theme controls how your store looks and how pages are laid out. An app adds functionality, such as reviews, subscriptions, loyalty programs or integrations with other systems. Many projects need both: a theme for the storefront experience and apps, public or custom, for features the theme cannot provide.
Which Shopify theme development agencies are based in the UK?
On this list, Swanky is based in Exeter, UK, while Underwaterpistol and Charle are both headquartered in London. Arctic Grey is headquartered in Silicon Valley but lists London among its offices. All four mention custom theme or Shopify Plus design and development work in their entries.
Can you hire someone to build a custom Shopify theme for your store?
Yes. Shopify theme development agencies and freelance Shopify developers build custom themes from a design, or adapt an existing theme to fit your brand and features. Several agencies on this list, such as Realm, Electric Eye, Swanky and Arctic Grey, state custom theme work in their entries. Ask for live store examples, how the theme will be maintained after launch, and whether you will be able to edit content in the Shopify theme editor yourself.
Choosing the right partner for your Shopify store can make all the difference in creating a seamless shopping experience and driving growth. The agencies highlighted in this article bring the creativity, technical expertise, and strategic insight needed to help your brand succeed online.
If you’re ready to elevate your store with a custom theme, app, or full-scale eCommerce solution, don’t hesitate to hire Shopify expert developers who can turn your vision into a high-performing reality. With the right team by your side, your Shopify store can stand out and thrive in today’s competitive market.
If you’re a Shopify Theme Design agency and want to feature your company on this list, email us with details or submit this form. After a quick evaluation, we’ll define whether it’s a valuable addition.
