"i only speak liquid" #71: App vs. Theme Customization: What Should You Build?

Hey everyone,

Here we go for Miguel’s 3rd of 4 edits of “i_only_speak_liquid”

Miguel (a Storetasker Member) is an experienced Shopify developer based in Colombia. He brings a wealth of operational experience having been on in-house teams, at agencies and now freelance.

Let’s GO 📚

What I’ve been thinking about:

When working on a Shopify store, one of the biggest decisions developers and merchants face is whether to customize the theme directly or build an app. Both approaches have their place, but choosing the right one can save time, improve maintainability, and optimize store performance.

Having built Shopify apps and worked with countless merchants, I’ve seen both approaches used effectively—but also seen them go wrong. So, when should you use theme customization, and when should you build an app? Let’s dive in.

When Theme Customization is the Right Choice

Theme customizations are often the fastest and most lightweight way to implement changes to a Shopify store. If a feature only affects the visual appearance or simple store logic, modifying the theme might be the best approach.

Best scenarios for theme customization:

• You need to adjust styling or layout (e.g., custom product page design, tweaking cart styles)

• You want to add Liquid logic that doesn’t require external data (e.g., showing a message based on cart total)

• The feature should work independently of apps (e.g., announcement bars or seasonal promos)

• You want the customization to be instantaneous without relying on API calls

When theme customization becomes a problem:

• Complex logic requires external databases or dynamic behavior

• You need features that persist across theme updates

• The functionality should work across multiple stores (e.g., reusable for clients)

• You want to avoid breaking changes when merchants switch themes

When You Should Build an App Instead

Apps are ideal when you need to add functionality that goes beyond what themes can do. Shopify apps allow for advanced logic, better security, and integration with third-party services.

Best scenarios for an app:

• You need to store data (e.g., customer preferences, loyalty points, subscriptions)

• You require custom backend logic (e.g., a price calculator, automatic discounts)

• The feature needs to be used across multiple themes (e.g., a reviews widget)

• You want better maintainability (e.g., updates without touching Liquid files)

• The feature requires Shopify’s Admin API, Storefront API, or GraphQL

Downsides of using an app:

• Can be overkill for small changes (e.g., a custom message on a product page doesn’t need an app)

• Apps rely on external requests, which could introduce latency

• Custom apps require ongoing maintenance, while themes are more "set it and forget it"

The Hybrid Approach: Best of Both Worlds?

In many cases, the best solution is a mix of both approaches. For example:

• An app could store data and provide an API, while a theme modification fetches and displays it

• A UI extension could inject content dynamically, while the theme handles styling

• Shopify’s metaobjects (see my previous article) can allow structured content storage without an external database

This balance keeps stores fast, maintainable, and scalable.

Final Thoughts: What’s Right for Your Project?

If the feature is simple, store-specific, and purely visual → Theme customization is likely the best choice.
If the feature requires data storage, complex logic, or scalability → An app is the way to go.
If you need the best of both worlds, consider hybrid solutions that combine both approaches.

At the end of the day, Shopify is flexible enough to allow both—so choose what makes sense for your project. 🚀

3 links you can’t miss:

📌 Shopify Theme Development Basics - Get started with Theme development
📌 Shopify App Development Guide - Get started with App development
📌 Polaris components - The open-source library of custom components that Shopify hasn’t yet released in their public Polaris repository.

1 app I like:

Shopify Search & Discovery - A fantastic app that integrates seamlessly with any theme and provides robust filtering functionality without requiring custom code.

One learning as a freelancer:

Give yourself some time. It's easy to get excited when work is coming in and set no limits for yourself. You can quickly lose track of time and burn out. It's great to have success, but also take time for yourself and enjoy the benefits of being a freelancer.

-Miguel