Two very different tools that share a name
On Shopify, the word "app" covers two things that behave nothing alike. A public app is built for a market: thousands of merchants install it, it has to support every edge case, and it makes money on subscriptions. A custom app — historically called a private app — is built for exactly one store, installed only there, and shaped around that store's actual operations.
Both extend Shopify through the same APIs. The difference is who they are for, and that single fact changes everything about cost, control, and fit. Choosing between them is less about technology and more about whether your problem is common or specific to your business.
What public apps are genuinely good at
Public App Store apps are the right answer more often than custom-app evangelists admit. They win when:
- The problem is common. Reviews, basic email capture, standard loyalty mechanics, help desks. Thousands of stores need the same thing, so a shared product is cheaper and more polished than anything bespoke.
- You need it this week. Install, configure, done. No build cycle.
- The vendor carries the maintenance. API version migrations, security patches, and Shopify platform changes are their problem, not yours.
For most stores, most of the time, a small set of well-chosen public apps is correct. The trouble starts when a store tries to force a public app to do something specific to its business, then bends its operations around the app's assumptions instead of the other way around.
Where custom apps start to win
A custom app becomes the better choice when the problem is specific to how your business actually works — and when the cost of getting it wrong is high enough to justify owning the solution. A few honest signals:
- Your workflow doesn't match any app's assumptions. You have B2B pricing tiers, complex bundles, multi-warehouse logic, or an ERP that a generic app can't model cleanly.
- You're paying per-order fees that scale against you. Many public apps charge by usage. At volume, a one-time build plus hosting is dramatically cheaper than a percentage of every order, forever.
- You need data to stay yours. A custom app reads and writes through the GraphQL Admin API into your own store and your own database. Nothing important is locked inside a vendor you don't control.
- Performance matters. A custom integration can use webhooks verified with HMAC, Shopify Functions for checkout logic, and metafields/metaobjects for structured data — without the extra scripts and trackers public apps inject into your storefront.
- You're on Shopify Plus and using checkout extensibility. Serious customization of checkout, post-purchase flows, and B2B is exactly where bespoke work pays off.
The recurring theme: custom wins when the app is part of your competitive operation, not a commodity feature you could buy from anyone.
A simple way to decide
Run any candidate problem through three questions.
1. Is this differentiating or just necessary? Necessary-but-common work (tax, basic reviews) should almost always be a public app. Differentiating work — the thing that makes your store operate better than competitors — is a candidate for custom.
2. What does it cost at 3x your current volume? Public apps with usage-based pricing can quietly become one of your largest line items. Model the cost at the scale you're aiming for, not today's. A custom build has a higher upfront cost and a flat run cost, so the lines cross somewhere — find out where.
3. Who owns the data and the logic? If the answer needs to be "us" — for compliance, for portability, or because the logic is genuinely yours — that points to custom.
If two or three answers point the same way, the decision is usually clear.
The middle path most stores miss
It is rarely all-or-nothing. The strongest setups use public apps for commodity work and a thin custom layer for the parts that are specific to the business. You might keep a public reviews app, a public help desk, and a public email tool — then build one custom app that handles your bundle pricing, syncs orders to your ERP through webhooks, and exposes a dashboard your team actually trusts.
That custom layer doesn't need to be large. It needs to own the few flows where generic tools force you to compromise. Done well, it removes per-order fees on your highest-volume operations, keeps your data first-party, and gives you something the App Store can't: software that matches your business exactly.
The mistake we see most is stores defaulting to public apps for everything and slowly accumulating compromise, or — at the other extreme — rebuilding commodity features from scratch out of pride. Neither is strategy. The right answer is deciding, problem by problem, where ownership is worth paying for.
If you're weighing a specific build, a Shopify audit is the fastest way to get an honest read on whether custom is justified, and you can see worked examples in our Demo Lab.