Every growing Shopify store hits the same question sooner or later: keep adding apps from the Shopify App Store, or pay to have a custom app built for your store? The right answer depends less on budget than on how specific your problem is. This guide explains the difference between a Shopify custom app and a public app, what each costs you over time, and a simple test for deciding which one you need.
Planning a project like this? See how our Shopify development services work, from a free scope to a fixed quote in 48 hours.
Public apps vs. custom apps: the short version
A public app is built once and sold to thousands of stores through the Shopify App Store. You install it in a few clicks, pay a monthly fee, and get a feature that solves a common problem — reviews, subscriptions, upsells, shipping rules.
A custom app is built for one store only. It is created in your Shopify admin or Partner account, uses the same Shopify APIs as public apps, and does exactly what your business needs. You pay for development once (plus hosting and maintenance), and you own the code.
| Public app | Custom app | |
|---|---|---|
| Built for | Thousands of stores | Your store only |
| Time to start | Minutes | Weeks |
| Cost model | Monthly subscription | One-off build plus hosting and support |
| Fit to your workflow | You adapt to the app | The app adapts to you |
| Data and code ownership | Vendor owns it | You own it |
| Roadmap | Vendor decides | You decide |
When a public app is the right choice
Public apps are the better option far more often than agencies like to admit. Choose one when:
- The problem is common. Product reviews, email capture, size charts and basic bundles are solved problems. A good public app has been tested on thousands of stores.
- You need it this week. Installation takes minutes; a custom build takes weeks.
- The monthly fee is small compared with a build. A $20–$50 per month app is hard to beat with custom development.
- You are still testing the idea. Use a public app to prove a feature earns its keep before investing in a custom version.
Signs you need a custom Shopify app
A custom app starts to make sense when the problem is specific to how your business works. Look for these signals:
- You are stacking apps to fake one workflow. Three or four apps plus a spreadsheet to handle one process usually means the process is unique to you.
- You need to connect a system nobody else uses. An in-house ERP, a regional 3PL or a legacy inventory database rarely has a ready-made connector.
- Your product needs a configurator. Made-to-order furniture, custom parts with fitment rules or B2B kits with dependencies are hard to model with generic apps.
- App fees keep climbing. Usage-based pricing on several apps can quietly exceed what a custom app would cost to build and run.
- You are worried about data access. Public apps store data on the vendor’s servers. A custom app keeps it in systems you control.
- Speed is suffering. Each app can add scripts to your storefront. Replacing several with one lean custom app can noticeably improve page speed.
A simple decision test
Ask three questions about the feature you need:
- Is the problem specific to my business? If thousands of stores have the same problem, look for a public app first.
- Does the best public app cover at least 80% of what I need? If yes, use it and live with the gaps. If you need heavy workarounds, consider custom.
- What will the public apps cost over three years? Add up subscription fees, usage charges and the staff time spent on workarounds. Compare that with a fixed quote for a custom build plus maintenance.
If the answers are “yes, no, more than a build”, a custom app is usually the better investment.
What a custom Shopify app can do
Custom apps use the same building blocks as public ones, so they can reach almost every part of your store:
- Admin API: read and update products, inventory, orders, customers and fulfilments.
- Storefront API and theme app extensions: add custom blocks and features to your theme without editing theme code.
- Shopify Functions: custom discount, shipping and payment logic that runs inside Shopify’s checkout.
- Checkout UI extensions (Shopify Plus): add fields, messages or upsells to checkout.
- Webhooks: react instantly when an order is placed, paid, fulfilled or refunded — for example, to push it to your ERP.
Common custom app projects include ERP and 3PL integrations, wholesale and B2B pricing portals, product configurators, custom loyalty programmes and internal tools that automate order handling. Many of these depend on integrations — our guide on connecting Shopify to your ERP explains the options.
What a custom app costs to own
The build is only part of the cost. When you compare options, include:
- Build: discovery, design, development and testing, quoted as a fixed price per phase.
- Hosting: most custom apps run on a small cloud server or serverless functions.
- Maintenance: Shopify releases a new API version every quarter, and each version is supported for at least a year. Your app needs updating as versions retire.
- Changes: new features as your business evolves.
Against that, a custom app removes subscription fees and usage charges, and you never lose a feature because a vendor changes its plan or shuts down.
Custom app vs. extending a public app
There is a middle path. Some public apps offer APIs or webhooks of their own, and a small custom app can sit between them and your other systems. That gives you the reliability of a mature public app with the connection or rule you were missing — often at a fraction of the cost of rebuilding the whole feature.
How to choose who builds it
If you decide on a custom app, the developer matters more than the idea. Look for a team that asks how your business works before talking about technology, gives you a written scope and fixed quote, builds on current Shopify APIs, and hands over the code and accounts. Our guide to hiring a Shopify custom app development agency walks through the questions to ask.
Frequently asked questions
Can a custom app be listed on the Shopify App Store later?
A custom app is created for a single store. If you later want to sell it, it has to be rebuilt as a public app and go through Shopify’s review, which adds billing, multi-store support and stricter requirements.
Do I need Shopify Plus for a custom app?
No. Custom apps work on every Shopify plan. Some extensions, such as checkout UI extensions, are only available on Shopify Plus.
Will a custom app slow down my store?
A well-built one should not. Back-end apps that sync data run outside your storefront entirely, and storefront features built as theme app extensions load only where they are used.
How long does a custom Shopify app take to build?
A focused integration or admin tool typically takes a few weeks. Larger apps with storefront features and several integrations take longer. You should get a stage-by-stage timeline with the quote.