Web · Shopify
Custom Shopify App Development
When Shopify's native features and the app store do not cover what your store needs, a custom app is the answer. We build private apps for internal workflows and public apps for distribution, using Remix, Shopify Functions, and the current Shopify CLI toolchain so the result is maintainable and built to Shopify's standards.
Built withRemixShopify FunctionsUI ExtensionsApp BridgePolarisShopify CLIShopify Dev MCP Server
TRUSTED BY TEAMS THAT SHIP
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What it is
What is custom Shopify app development?
A custom Shopify app extends what Shopify does natively: adding logic to the checkout, embedding admin tools, modifying discount and shipping behaviour at the function level, or building surfaces that no off-the-shelf app covers. Private apps serve a single store's internal needs. Public apps go through Shopify's review process and can be listed on the App Store or distributed directly to merchants.
The modern Shopify app stack uses Remix as the application framework, Shopify Functions for server-side logic (discounts, shipping, payment customisation, and order routing), and UI Extensions for embedded admin and checkout surfaces. The Shopify Dev MCP Server, which became part of the standard agency workflow in 2026, lets developers scaffold apps, run GraphQL operations, and generate validated code inside tools like Cursor and Claude. We check whether an existing app store solution fits your need before recommending a build, and we will say so clearly when it does.
What's included
What a custom Shopify app build includes
Remix app scaffoldA Remix application structured to Shopify's current app architecture with OAuth, session management, and webhook handling.
Shopify FunctionsServer-side function logic for discounts, shipping rules, payment methods, and order routing compiled to WebAssembly.
UI ExtensionsEmbedded checkout, post-purchase, admin, and POS extensions built with Polaris and App Bridge.
GraphQL API integrationAdmin and Storefront API queries and mutations covering the data your app needs to read and write.
Webhooks and event handlingReliable webhook registration and processing so your app responds to Shopify events without data loss.
App review readinessPublic apps are built to pass Shopify's review requirements, including GDPR webhooks, billing API, and security standards.
Testing and documentationEnd-to-end testing across install, billing, and core flows, plus developer documentation for your team.
How we work
How we build a custom Shopify app
1Requirement and fit check
We map your requirement to the Shopify platform and confirm a custom app is the right solution versus an existing app or a native feature.
2Architecture and scope
We define the app type (private or public), the Functions and Extensions needed, and the API surface before writing code.
3App build
We build the Remix application, Shopify Functions, and UI Extensions using Shopify CLI and the Dev MCP Server for validated code generation.
4API and webhook integration
We connect GraphQL queries, mutations, and webhooks and test them against a development store with realistic data.
5Testing and review prep
We run end-to-end tests across install, uninstall, billing, and all core flows, and prepare public apps for Shopify's review process.
6Deploy and handover
We deploy to production, confirm all webhooks are registered, and hand over documentation and support contacts.
Why it matters
What a custom app makes possible
The right custom app removes a hard ceiling on what your store can do without patching together multiple third-party tools.
Logic Shopify does not ship
Shopify Functions let you run custom discount, shipping, and payment logic directly inside Shopify's checkout without workarounds.
Admin tools that fit your workflow
Embedded UI Extensions add purpose-built admin surfaces so your team works inside Shopify rather than switching between systems.
One solution, not several
A single custom app built for your exact need is often faster, cheaper to maintain, and more reliable than stacking three app store tools.
Who this is best for
The right fit
Best for stores with workflow or logic gaps the app store cannot fill
Merchants who need custom checkout logic not available through Shopify Functions off the shelf, internal admin tools tailored to their team, or a public app they want to distribute to other merchants.
You might not need a custom app
If your requirement is connecting Shopify to an external system like an ERP or CRM rather than extending Shopify's own logic, Shopify Integration is likely the faster and more cost-effective route.
FAQs
Common questions about Shopify app development
What is the difference between a private app and a public app?
A private app is built for a single store and does not go through Shopify's review process, making it faster to build and deploy for internal workflows. A public app can be listed on the Shopify App Store or distributed to multiple merchants, but must pass Shopify's review requirements including GDPR webhooks, billing API compliance, and security standards.
What are Shopify Functions and when do I need them?
Shopify Functions are small programs that run inside Shopify's infrastructure to customise discount, shipping, payment, and order-routing logic at the checkout level. You need them when you want behaviour that standard discount codes and shipping rules cannot produce, for example tiered B2B pricing, complex free-shipping thresholds, or conditional payment method visibility.
How long does it take to build a custom Shopify app?
A focused private app with one or two Functions or Extensions typically takes 4 to 8 weeks. A public app with a full billing integration, review-ready GDPR handling, and multiple Extensions takes 8 to 16 weeks depending on scope. We scope this clearly in discovery before any code is written. [verify]
What framework do you use to build Shopify apps?
Remix is Shopify's recommended framework for new apps and the one we use for all builds. It handles OAuth, session management, and the Shopify API integration patterns that Shopify's tooling is built around. We use Shopify CLI for scaffolding and the Shopify Dev MCP Server for validated code generation throughout the build.
Can you extend or fix an existing custom app?
Yes, provided the existing app is built on a maintainable codebase. We will review the code first and give you an honest assessment of whether extending it or rebuilding on the current Remix stack is the better path.
Do custom apps affect store performance?
Server-side apps and Shopify Functions run on Shopify's infrastructure and have no impact on storefront performance. UI Extensions are embedded surfaces that Shopify renders, so their performance is within Shopify's control. Storefront-injected scripts are the common performance risk; we avoid them where the platform offers a native extension point instead.
Selected work
Shopify projects, by the problem they solved
Filter by what you are facing. These are representative project types; real case studies and figures are shared on request.
Voices
What merchants say
Have a workflow a Shopify app could solve?
Get a free build audit. We will map your requirement to the Shopify platform, tell you honestly whether a custom app is the right solution, and scope the work before you commit.
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