On Shopify, you need a custom app when your requirement can't be met by theme settings, by Shopify's built-in tools and Shopify Flow, or by a ready-made app from the App Store. This usually happens in three situations: when you need to exchange data with a system that has no ready-made connection (such as an ERP, warehouse software or an e-invoicing integrator), when your business rules go beyond what ready-made apps' settings allow, and when several apps chained together can't run a single workflow reliably. Most other needs can be met in faster ways that require less maintenance.

We covered the building blocks a custom app is developed with and how the process works in a separate article. This article focuses on the moment of decision: which route should you choose for the need in front of you?

Our article on the building blocks of a custom app and the development process: Shopify custom app development

Four Options, Four Different Layers

Theme Customisation

The look of the store and the information shown on its pages are the theme's job. Adding sections and blocks in the theme editor, and connecting information such as a size chart, ingredient list or usage instructions defined with metafields and metaobjects to the page as a dynamic source, often requires no code. Deeper changes are made in the theme's Liquid templates.

Built-in Tools and Shopify Flow

Shopify Flow is a free Shopify app that lets you build automations made of triggers, conditions and actions, and it's available on the Basic, Grow, Advanced and Plus plans. It's ideal for jobs such as tagging orders that contain certain products, notifying the team when stock runs low or holding risky orders for review. The action that sends an HTTP request to an external system is available on Grow and higher plans, while tasks that custom apps add to Flow are available on the Plus plan.

App Store Apps

For needs that many stores share, such as product reviews, loyalty programmes, email marketing and shipping integration, there are ready-made apps on the App Store. These public apps are reviewed by Shopify before they're listed. According to Shopify's documentation, public apps that contain Shopify Functions, which change rules in the checkout process, can also be used on every plan, apart from exceptions for some APIs.

Custom App

A custom app is developed only for your store and works with your business rules. Since 1 January 2026, new custom apps have been created in the Dev Dashboard rather than in the Shopify admin. It's important to know the plan limits from the start: according to Shopify's developer documentation, only Plus stores can use custom apps that contain Functions, and UI extensions added to the information, shipping and payment steps of checkout also work only on Plus.

5 Questions to Help You Decide

When a new need arises, ask these questions in order. The first “yes” usually points to the right route.

1. Is the need only about appearance or the information on the page?

If so, start with theme customisation. Defining a metafield for product-specific information, or a metaobject for reusable content blocks, is usually a lighter solution than installing an app for the same job, and it doesn't load extra code onto the storefront.

2. Do you want to respond to an event in the store with a simple rule?

Jobs that can be described as “when an order comes in and this condition applies, do this” should be tried with Flow first. Flow's ready-made templates cover many common scenarios, and your team can change the rules without writing code.

3. Do other stores have the same need?

If so, there's very likely a solution on the App Store. Before installing an app, check the following:

  • Maintenance: The date of the last update and recent reviews show whether the app is being developed regularly.
  • Built for Shopify: This status, which Shopify gives to apps that meet its performance, design and integration criteria, is a good first filter.
  • Storefront impact: Does the app work with theme app extensions, or does it add scripts directly to the theme code? Does it leave code behind when it's removed?
  • Permissions: Does the app ask for access to more data than it needs to do its job?
  • Total cost: The monthly fee, per-order fees and the total annual amount.

4. Do you need a business rule in the checkout process?

Rules such as discount set-ups, hiding a shipping or payment option under certain conditions, or validating the cart work with Shopify Functions. If you're not on Plus, you use a ready-made app that contains Functions; on Plus stores, if a ready-made app doesn't meet the need, you can write your own rule with a custom app.

A note for Plus stores using Shopify Scripts: according to Shopify's announcement, Scripts can no longer be edited from 15 April 2026 and stopped working on 30 June 2026. Functions are the new equivalent of these rules.

5. Do you need to exchange data with a system that has no ready-made connection?

This is where a custom app really comes into its own. Stock, price and order synchronisation with your ERP, an e-invoicing flow specific to your integrator, passing shipment details to warehouse software, or management reports that combine data from several systems often require an app built specifically for your brand. Because these apps run on the server side, they don't add code to the storefront.

Example Scenarios

  • Adding a size chart to the product page: A metaobject and the theme. No app needed.
  • Notifying the warehouse about orders that contain a particular brand's products: Shopify Flow.
  • Hiding cash on delivery for orders above a certain amount: A ready-made, Functions-based app that customises payments; on Plus, a custom app if needed.
  • Product reviews and a loyalty programme: Ready-made apps from the App Store.
  • Stock and order synchronisation with Logo, Mikro or Nebim, if there's no ready-made connection: A custom app.
  • Several apps that touch the same order without knowing about each other: Consolidating the workflow into a single custom app.

Before You Decide on a Custom App

A custom app is software that belongs to you, and it needs maintenance. Shopify releases API versions every quarter, and each stable version is supported for at least 12 months; the app needs to be updated in line with this schedule. When deciding, don't just pin down the development cost; get clear answers to these questions too:

  • Who will hold the app's code and hosting?
  • When a record fails to transfer, who will notice, and how?
  • Who will update the app when the other system (the ERP or integrator) changes its own API?

Frequently Asked Questions

Can a custom app be used on the Basic plan?

Yes. Custom apps that work with the Admin API and webhooks can be used on plans other than Plus too. According to Shopify's developer documentation, apps with custom distribution can also access protected data such as a customer's name, address, phone number and email; the plan-dependent restriction on this access applies to legacy custom apps created in the admin. The Plus-only features are custom apps that contain Functions, UI extensions added to the information, shipping and payment steps of checkout, and custom app tasks in Flow.

Will a custom app slow down the store?

An integration that runs on the server side and talks to Shopify through the API doesn't add code to the storefront. If a part needs to appear on the storefront, it can be added with a theme app extension so that it loads only on the pages where it's needed.

Can ready-made apps and a custom app be used together?

Yes. For most stores, the most balanced set-up is ready-made apps for common needs and a single custom app for the brand-specific workflow.

Conclusion

The right order is usually this: first the theme and Shopify's own tools, then the App Store, and a custom app last. This order avoids unnecessary code and the burden of monthly subscriptions while directing your investment towards the workflows that are truly unique to you. As an official Shopify Partner, we at Booster Wizard follow the same order in our projects, and where a ready-made solution isn't enough, we develop the custom app and take care of its maintenance.

To see your store's current set-up, you can start a free store audit and, to assess an integration need together, explore our Shopify Partner services .