Custom Shopify App or Off-the-Shelf? How to Decide

Most of a Shopify store runs well on Shopify itself and a handful of good apps. Then there is the one job that does not fit anything you can install, and the team works around it with a spreadsheet tab or a second app that half does the job.

Before building anything, ask a simpler question: where should this logic live? Shopify offers several answers, and custom work earns its place only when none of them fits.

Start with the apps you already have

A common thread on the Shopify Community describes the problem well: too many apps slow the store down, but removing one breaks a workflow. The replies point the same way: the biggest gains come from consolidating apps that overlap and from limiting what loads on every page, not just from cutting the number of apps.

Put every installed app in one of three piles:

Core to the business. It drives revenue, saves real time or runs an essential operation. Keep it.
Overlapping. Two apps do the same job, or one does a small part of what another already covers. Pick one.
One small job, done awkwardly. You use a single feature, it fits your process badly, and nobody would miss the rest of the app.

The third pile is where custom work is worth a look. An uninstalled app can leave code in the theme, so test removals on a duplicated theme first.

The four places store logic can live

Shopify Flow

Shopify Flow is a free Shopify app on the Basic, Grow, Advanced and Plus plans. Its workflows are built from triggers, conditions and actions: “when an order is tagged, if the total is over a threshold, notify the team.” If your job reads as “when X happens, do Y” inside Shopify, start here.

Flow’s Send HTTP request action, on the Grow, Advanced and Plus plans, can also call an outside system. It waits up to 30 seconds for a response and can retry for up to 24 hours. Something on the other end still has to receive that request and do the work.

Shopify Functions

Shopify Functions customize Shopify’s backend logic: discounts, payment and delivery options, cart and checkout validation, bundles and fulfillment constraints. Functions are delivered inside an app, either one you install from the App Store or one built for you. One plan rule matters: only stores on Shopify Plus can use custom apps that contain Function APIs, while public apps with functions work on any plan.

A public app

If an app on the Shopify App Store already does the job, start there. Public apps serve many merchants and go through App Store review, as Shopify’s app distribution guide describes.

A custom app

A custom app is built for one merchant: a single store, or several stores in the same Plus organization. It skips App Store review, and it cannot charge through Shopify’s app billing. It fits when the job depends on your own data, your other systems or your own screens and approval steps.

A practical rule of thumb: start with Flow, reach for Functions when checkout logic has to change, and build a custom app when the workflow needs its own screens, data or connections.

Two 2026 changes to know first

Custom apps now come from the Dev Dashboard. According to Shopify’s help center, custom apps are created and managed in the Dev Dashboard, and apps made in the admin before January 1, 2026 are managed there as legacy apps. Shopify’s developer docs state that you can no longer create new admin-created custom apps; existing ones keep working. Do not delete a legacy app until its replacement runs, because you cannot recreate it the old way.

Shopify Scripts ended on June 30, 2026. Shopify’s migration guide says Scripts still published were deactivated and no longer work. Their logic moves to Shopify Functions. If your Plus store relied on Scripts for tiered discounts or hidden payment methods, list what each Script did, check whether a public app now covers it (Shopify’s migration docs map each Script type to a Function API), and build only the gap.

Doing the math

Another Community discussion suggests a useful comparison: what a set of small apps costs you over months and years, against an estimate for building the one feature you actually use. Add the cost of depending on a tool you do not control, then shortlist only the apps that could realistically be replaced. Many stores end up with a balance: essential apps stay, a few simple features get built.

When custom is the answer

Custom work makes sense when:

the job is specific to how your team works, and every app forces a workaround;
it depends on data or systems outside Shopify;
you need your own approval steps before something changes;
a Shopify change removed something you relied on.

If that describes a row on your list, our custom solutions page explains the kinds of work we take on and what a short brief should include.

Have a workflow no ready-made app fits? Talk to us and we will reply with how we would approach it.