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

As your ecommerce business grows, the more complex operations take place to manage diverse processes, and the more tailored functionality you might need. That's where custom Shopify apps take place since they're built around your specific workflows and your particular business logic. This guide reviews how to build a Shopify app that works exactly in line with your needs.

TL;DR: Building a Shopify custom app

• A custom Shopify app, unlike a public app, is not listed in the Shopify App Store and is built specifically for your store's needs.

• Among custom app benefits are an exact fit for your business logic and internal systems, code and data ownership, no recurring subscription fees, and improved performance.

• Custom app limitations include higher upfront costs for development, extended development timelines, and necessary app maintenance.

• Signs you need a custom app are tool fragmentation, operational friction, performance issues, demand for better data visibility, and higher security requirements.

• The Shopify app's three main parts are user interface, backend part, and Shopify APIs.

• To build a custom Shopify app, you need to follow ten steps:

1. Set up the development environment
2. Choose your tech stack
3. Create the app structure
4. Implement the authentication layer
5. Connect to Shopify APIs
6. Build core features
7. Register webhooks
8. Test the app
9. Deploy the app
10. Install and use it

What is a custom Shopify app?

A custom Shopify app is an extension designed to solve your specific problem and to be easily integrated into your business logic. Unlike apps in the Shopify App Store, which are built to be compatible with thousands of other stores, a custom app is developed for a single store or a specific store segment. Typically, it’s not publicly listed, doesn’t go through Shopify’s app review process, and is installed directly using API credentials.

Understanding Shopify app types

What's the difference between public, private, and custom Shopify apps?

• Public apps are free and paid apps listed in the Shopify App Store in various categories, from email marketing to loyalty programs. These apps solve common problems, and they are available to any merchant. They're built in line with Shopify app requirements and best Shopify app development practices. Before an app is visible in the store, you need to submit it for review. As an example, Klaviyo and Afterpay developed their public Shopify apps for easy integration of their services with the platform.

• Private apps were deprecated in 2022 due to security limitations and replaced with custom apps that are based on the OAuth 2.0 authentication standard.

• Custom apps are developed for a specific store to add tailored functionality. They rely on Shopify’s APIs and are not listed publicly. API credentials are generated right in the Shopify admin, and there’s no need to comply with App Store listing guidelines.

Why businesses invest in Shopify custom apps

As businesses scale, they develop workflows that are often not fully compatible with standard ecommerce tools. These might include:

• Multiple pricing tiers for B2B customers

• Complex inventory management across multiple locations

• Custom fulfillment logic tied to CRM and ERP systems

• Unique customer journeys or loyalty programs

• Advanced reporting with data across multiple sources

Public apps often have limits and can't adapt to such complexity. Eventually, you try to bring together multiple tools that don't fully solve your tasks and negatively impact your store's performance.

A custom app, instead, lets you build a coherent system without slowing down your website. And the important point – you don't need to share your data with third-party services and you fully own and control the app logic. At the same time, these benefits are only available at the cost of custom Shopify app development.

Let's sum up the pros and cons of custom Shopify apps.

Advantages of custom Shopify apps:

• Exact fit for your business logic

• Full code and data ownership

• No monthly subscription fees

• Tight alignment with your internal systems

• Better website performance

Limitations of custom Shopify apps:

• Higher upfront costs for development

• Necessary ongoing maintenance

• Stretched development timelines

Signals that it’s time to create a custom app

Not every business needs a custom Shopify app. In many cases, existing tools are more than sufficient. But there are clear signals that indicate when you’ve outgrown them.

• Tool fragmentation. If you use multiple apps to deal with a single workflow and still experience inconsistencies, it's a sign to consider building a custom app.

• Operational friction. If you handle a lot of manual processes, repeated data entries, and frequent errors, it may point to missing automation that pre-built tools can’t provide.

• Performance issues. Each installed app includes scripts and API calls that impact your store's speed. Replacing several apps with one effective solution can significantly improve performance.

• Data visibility. As your business grows, you need to combine data from Shopify and external and internal systems. If your current tools can’t deliver that, a custom app may be a great option.

• Compliance and security requirements. If you run a business in an industry with strict data management standards, public apps would be unsuitable, while custom apps allow you to handle data more safely.

What do you need before custom Shopify app development starts?

Building a Shopify app requires a few essential elements to be in place.

• A Shopify Partner account gives you access to the Partner Dashboard, where apps are created and managed.

• The development store is free and essential to test your app without affecting ongoing store processes.

• Developer permissions with collaborator or staff account access are a must if you work with an existing Shopify store.

• Shopify’s API knowledge is critical. Admin API and Storefront API are now powered by GraphQL, but you should also be familiar with the REST API.

• Clarity around your app’s purpose to precisely understand which problem you’re solving and which functionality not to include.

How to plan Shopify custom app development

If there’s one stage that determines the success of a custom Shopify app, it’s planning.

1. First, you need to identify current problems by analyzing your workflows. Where do errors and delays occur? Where do systems fail to connect? Where do you spend too much time on manual processing?
2. Next, prioritize features you want to implement first by dividing all of them into must-have and nice-to-have categories. Then, gather the requirements for the feature to implement. Before Shopify custom app development, define who will interact with the app – customers or company staff? Each group introduces different requirements for access, interface design, and functionality.
3. Finally, consider technical constraints. Some API endpoints and features are only available for the Shopify Plus plan. So, check if your current plan doesn't limit the expected functionality. Will you primarily use the Admin API, the Storefront API, or both? Will you need access to the Checkout Extensions API or Functions API? You need to have these questions answered.

How Shopify apps work: A closer look at the architecture

How Shopify app works

If you break it down, a Shopify app is a combination of a few parts that handle different jobs.

• On the surface, there’s the interface handled with the frontend layer. That’s what a merchant interacts with day to day. In most cases, it sits directly inside the Shopify admin and follows the Polaris design system.

• Then there’s the backend. This is where things actually happen. It deals with logic, keeps track of data, and sends requests back and forth to Shopify. The exact stack depends on the team — Node.js, Rails, Python.

• To get any data in or out, the app uses Shopify’s APIs. That’s how it can, say, pull order details or update stock levels. Without that layer, the app wouldn’t be able to do much.

Access is handled separately. When someone installs an app, Shopify asks them to approve what the app can see and do. After that step, the app receives an access token (OAuth 2.0) and uses it for future requests.

One more piece that’s easy to miss: apps don’t constantly check for updates. Instead, they wait. Shopify sends webhooks when something changes — new order, product update, whatever it is — and the app reacts to that. It’s simpler and avoids unnecessary API calls.

Step-by-step process: How to build a Shopify app

If you’re creating a Shopify app from scratch, the process is fairly straightforward in theory. In practice, it could be more confusing since too many business specifics should be taken into account. If you need help managing the technical part, contact the DigitalSuit team. We have deep expertise in building Shopify apps.

The app building process usually goes through ten steps.

1. Set up the environment.

Shopify CLI is the first thing to install, then Node.js (v18 or newer), plus whatever package manager you normally use — npm, yarn. You’ll also need a development store. Most people set that up in the Partner Dashboard before doing anything else.

2. Pick your stack.

From there, you decide how you actually want to build it. Shopify pushes Node.js with Remix by default — that’s what their CLI generates — but it’s not a requirement. Some teams stick with Rails, others use Laravel or Python. As long as your backend can deal with OAuth and API calls, you’re fine. On the frontend side, if the app lives inside the Shopify admin, people usually rely on Shopify App Bridge and Polaris. It just saves time.

3. Generate the app skeleton.

Once the basics are in place, you can generate the app itself. Running shopify app init gives you a starting point — folders, config, and an initial OAuth setup. It’s not production-ready, but it gets you moving. You’ll still need to define scopes – what data the app can access – and set redirect URLs in the dashboard manually.

4. Implement authentication

Authentication tends to be one of those things you don’t want to leave for later. Shopify uses OAuth, so when someone installs your app, they’re asked to approve access. After that, your backend gets a code, exchanges it for an access token, and keeps it for future requests. That token is basically your key to the store, so it has to be stored properly.

5. Connect to Shopify APIs

Once that’s working, with your access token, you can start making API calls. Most of it goes through the Admin API — products, orders, customers, inventory, all of that. The Storefront API is relevant for customer-facing features like custom storefronts or Shopify headless setups. Shopify has been pushing GraphQL for a while now, mostly because it’s more flexible, though REST hasn’t fully gone yet.

6. Build core features

That's where your prior planning pays off. At this step, you start implementing feature by feature in line with your business logic. You build a feature, test it in your development store, adjust, and repeat. If the app is embedded, using Polaris helps keep things consistent.

7. Use webhooks

Register webhook subscription for the events you want your app to react to, such as new orders, inventory updates, and customer data changes. Once you're subscribed, Shopify sends a request when something happens, and your app reacts. You do need to verify those requests, and it’s worth handling duplicates since they can arrive more than once.

8. Test your app

Functional testing covers the basics: does each feature work as expected? However, problems usually show up around the edges — rate limit errors, broken payloads, race conditions. Use Shopify’s API rate limit documentation to understand the constraints.

9. Deploy the app

When everything feels stable, you deploy. Hosting can be almost anything — Heroku, AWS, Vercel, Fly.io, Google Cloud. Set up environment variables for your API keys and secrets, set up SSL, and have at least basic monitoring in place. Security-wise, OWASP guidelines are a decent reference if you’re not sure what to check.

10. Install and use the app

After that, installation is pretty straightforward. Custom apps don’t go through a review process. You generate API credentials in the Partner Dashboard, install the app on the target store, configure it, and start using the app.

How to make a Shopify app work: Challenges and their solutions

Even with a solid plan, Shopify app builds rarely go exactly as expected. A few issues tend to come up again and again.

Rate limits are one of the first things people run into. Shopify doesn’t let you hit the API endlessly — both REST and GraphQL have limits. If your app makes too many requests too quickly, you’ll start getting throttled. The usual way around it is pretty standard: queue requests, cache where it makes sense, and don’t retry instantly — back off gradually. Shopify Plus stores get a bit more headroom, but it’s still something you have to design around.

Another thing that creeps up over time is API versioning. Shopify updates its API every quarter and phases older versions out. It’s not a one-time task — you have to keep an eye on it and plan updates as part of ongoing maintenance, otherwise things will eventually break.

Then there’s scope. Midway through a build, it’s tempting to add another feature. Sometimes it’s needed, but often it just complicates things — more code, more edge cases, and more testing. Timelines stretch quickly if you’re not careful. Security is less forgiving. If something goes wrong here, it’s not just a bug — it can expose store data. Token storage, webhook verification, input validation — these aren’t optional. They need to be handled properly from the start, not patched in later.

And finally, performance at scale. An app that works fine with a handful of orders can behave very differently under load. If traffic spikes — Black Friday is the obvious example — weak spots show up fast. It’s worth testing for that kind of scenario before it actually happens.

Building a custom Shopify app with DigitalSuits

A custom app is rarely a small commitment. It takes time, budget, and some ongoing attention after launch. But if what’s available in the App Store doesn’t fit your workflows, a custom app can be worth it.

How to create an app for a Shopify store in the most optimized way?

Most of it comes down to preparation. Being clear about what you’re trying to solve helps more than any technical decision later on. The stack matters, of course, but unclear requirements tend to cause more issues than the choice between, say, Node and Rails.

Some teams build everything in-house, others bring in outside help — both approaches work. What matters is having a structure to follow, so you’re not making decisions on the fly.

DigitalSuits develops custom Shopify apps with attention to every step, from early planning to deployment and support. If you’re considering a custom build, we’d welcome a conversation about your requirements. You can also explore our deep dive on how much it costs to build a Shopify app to even more deeply understand the context.