Creating a Custom Shopify App: How to Build and Deploy Tailored Shopify Functionality

Introduction

While Shopify’s App Store offers thousands of plugins to extend store functionality, sometimes merchants need more specific or integrated solutions. That’s where custom Shopify apps come in. Whether you’re building a private solution for a single store or a custom workflow for multiple clients, developing a Shopify app gives you full control over backend logic, data integrations, and user experiences.

In this guide, you’ll learn how to create a custom Shopify app from scratch, including setup, authentication, using Shopify’s Admin API, and deployment best practices. By the end, you’ll have the foundation needed to build, test, and launch your own fully functional Shopify app.

What Is a Custom Shopify App?

A custom Shopify app is a private application built specifically for one or more Shopify stores. Unlike public apps listed on the Shopify App Store, custom apps are tailored to individual business needs and can:

• Add new admin features or dashboard tools
• Connect to third-party systems (e.g., ERP, CRM)
• Automate custom workflows (e.g., tagging, order routing)
• Enhance frontend functionality (e.g., custom pricing rules, upsell widgets)

You can create custom apps using Shopify’s API and deploy them either as embedded apps (within the Shopify Admin interface) or standalone apps.

Prerequisites

Before starting, make sure you have the following:

• A Shopify Partner account
• A development store or access to a live store (for testing)
• Node.js and npm installed
• A public HTTPS server (for development, use ngrok)
• Familiarity with JavaScript, REST or GraphQL APIs, and basic OAuth 2.0

Step-by-Step: How to Build a Custom Shopify App

Step 1: Set Up Your Development Environment

Install the Shopify CLI:

bashCopyEditnpm install -g @shopify/cli

Create a new app project:

bashCopyEditshopify app create node

You’ll be prompted to select:

• Your app name
• Preferred language (Node.js or Ruby)
• App type (custom/private/public)

Navigate into your project folder:

bashCopyEditcd your-app-name

Step 2: Connect to a Development Store

Login via CLI:

bashCopyEditshopify login

Then connect your app to a development store:

bashCopyEditshopify app dev

This command spins up a tunnel (using ngrok), installs the app on your development store, and opens a local dev server.

Step 3: Set Up OAuth Authentication

Shopify apps must be authenticated via OAuth to access store data.

Out of the box, Shopify CLI scaffolds OAuth flow and manages access tokens. You can find the logic in:

bashCopyEdit/web/shopify.js

This includes:

• Verifying request headers
• Handling token generation
• Saving sessions (in memory or database)

Step 4: Use Shopify Admin API or GraphQL

Once authenticated, you can make API calls on behalf of the store.

Example (REST API – fetch products):

javascriptCopyEditconst session = await Shopify.Utils.loadOfflineSession(shop);
const client = new Shopify.Clients.Rest(session.shop, session.accessToken);

const products = await client.get({
  path: 'products',
});

Example (GraphQL API):

javascriptCopyEditconst query = `
{
  products(first: 5) {
    edges {
      node {
        id
        title
      }
    }
  }
}`;

const client = new Shopify.Clients.Graphql(session.shop, session.accessToken);
const response = await client.query({ data: query });

Step 5: Build Your Custom App Logic

Now, implement your app’s core functionality. Some examples:

• Custom order workflow: Tag high-value customers automatically
• ERP sync: Push order data to an external system
• Shipping logic: Override shipping rates based on product metadata
• UI enhancement: Create embedded UI components via Shopify App Bridge + Polaris

Step 6: Embed the App in Shopify Admin

For a seamless user experience, make your app embedded inside the Shopify admin dashboard.

Use:

• Shopify App Bridge – for secure, embedded app context
• Polaris – Shopify’s design system for admin UIs

Example: App Bridge Initialization (React)

javascriptCopyEditimport { Provider } from "@shopify/app-bridge-react";
import { AppProvider } from "@shopify/polaris";

const config = {
  apiKey: API_KEY,
  host: new URLSearchParams(location.search).get("host"),
  forceRedirect: true,
};

<Provider config={config}>
  <AppProvider i18n={translations}>
    <YourApp />
  </AppProvider>
</Provider>

Step 7: Test Your App Thoroughly

• Use multiple test cases (different product types, orders, workflows)
• Check OAuth session storage and expiry
• Monitor for rate limits and error handling
• Use Shopify’s GraphiQL app to test GraphQL queries

Step 8: Deploy the App

Once testing is complete:

• Host your app backend on a production server (e.g., Heroku, Vercel, AWS)
• Point your app URL in the Partner dashboard to your live domain
• Reinstall the app on the store using the production URL
• Monitor performance, security, and usage

For custom apps used by a single merchant, you don’t need app review—they can be installed directly.

Real-World Use Cases for Custom Shopify Apps

Tips for Advanced Custom App Development

• Use webhooks for event-driven logic (e.g., orders/create, customers/update)
• Implement rate limit handling (Shopify uses leaky bucket algorithm)
• Encrypt and securely store API keys and tokens
• Use Shopify’s Billing API if you plan to monetize your app
• Write clear documentation if the app will be used by clients or teams

Conclusion

Creating a custom Shopify app allows you to tailor functionality exactly to business needs—something no off-the-shelf app can always provide. Whether you’re building internal tools, integrating third-party services, or enhancing store features, Shopify’s robust APIs and developer tools give you the power to create powerful, secure, and seamless solutions.

With a solid understanding of the setup, APIs, and authentication flow, you can go from idea to working custom app—backed by the full flexibility of Shopify’s platform.