Shopify App Development
Custom apps for one store and public apps for the Shopify App Store, built on Shopify's current extension platform.
01 What it is
Shopify App Development: what it is
Shopify app development is the work of building software that extends a Shopify store through Shopify's APIs and extension points. Apps come in two kinds. A custom app serves one merchant: you install it on your own store, or on the stores in one Plus organization, and it skips App Store review. A public app serves many merchants, lists in the Shopify App Store, and must pass Shopify's review. Shopify fixes the distribution method once you choose it, so that decision comes first.
An app is a web backend plus extensions. The backend talks to the GraphQL Admin API, which Shopify treats as the primary API now that it has marked the REST Admin API as legacy, and it receives webhooks for events such as orders and product updates. Extensions run inside Shopify: Shopify Functions change discount, shipping and payment logic on the server, checkout UI extensions add fields and content to checkout, admin extensions add actions and blocks to admin pages, and theme app extensions add blocks to the storefront.
Embedded apps render inside the Shopify admin with App Bridge and Shopify's Polaris web components, so merchants work in an interface that matches the rest of their admin.
02 Who it's for
Who it is for
A custom app suits a merchant with a rule or integration no App Store app covers. Examples include tiered wholesale discounts, a shipping rule tied to your warehouse, an ERP sync, or a staff tool inside the order page. Shopify has retired Shopify Scripts, and Functions now carry this kind of discount, shipping and payment logic. Plan matters here: Shopify's documentation limits custom apps that contain Functions to Plus stores, and it limits checkout UI extensions on the information, shipping and payment steps to Plus as well. Merchants on other plans can use Functions through public apps from the App Store and can extend the thank-you and order status pages. Shopify changes these rules, so check its documentation for your plan.
A public app suits a founder who wants to sell software to Shopify merchants. You take on App Store review, Shopify's billing system for charges, the mandatory privacy webhooks, and support for stores you have not seen.
An app is the wrong choice if an existing App Store app does the job at a fair monthly fee, if Shopify Flow can automate the task, or if a theme change solves it. We check those three options before we propose a build.
03 How to use it
How a project runs with devinsta
The engagement opens with a free 30-minute strategy call. You describe the store, the plan it runs on and the behavior you want. We tell you if an app is the right route and which extension points it would use.
Discovery turns that into a specification. We list the API scopes the app needs, the webhooks it subscribes to, the data it stores, and each extension with a sketch of its screen. For public apps we add the pricing model and the App Store requirements the app must meet. You approve the specification before the build starts.
We build in two-week sprints with a demo each week on a development store. You install the work in progress, place test orders and see the Function or extension run. Shopify CLI gives us a repeatable way to release app versions, so each demo matches a tagged version in your repository.
Handover delivers the repository, the hosting account, the app record in your Shopify Partner organization, and a runbook for releases. Public app clients also receive the listing copy, screenshots and the submission we prepared for review.
04 How to deploy
How we deploy it
Shopify hosts the extensions and you host the backend. Functions, checkout UI extensions, admin extensions and theme app extensions deploy to Shopify through Shopify CLI as part of an app version. The web backend, its database and its webhook endpoints run on hosting in your own account; we use Shopify's current app template, which is built on React Router, on a Node host with Postgres unless your stack calls for something else.
Security follows Shopify's requirements. The embedded app authenticates with session tokens, the backend verifies the HMAC signature on each webhook and app proxy request, and the app requests the narrowest API scopes that do the job. Apps that read customer names, emails or addresses need Shopify's protected customer data approval. Public apps must answer the three mandatory compliance webhooks for customer data requests and deletion.
Public apps go through App Store review, where Shopify tests installation, billing, performance and the listing. Reviewers can send the app back with changes, so we test against the checklist before submission and do not promise a review date.
After launch we monitor webhook delivery failures, API rate limits and Function errors, and we track the API versions Shopify releases each quarter so the app stays on a supported one.
05 What we provide
What you get from us
- Written recommendation on custom app, public app, existing App Store app or Shopify Flow
- Technical specification with API scopes, webhooks, data model and extension list
- App backend on the GraphQL Admin API with verified webhooks and app proxy routes
- Shopify Functions for discounts, delivery and payment customization, and cart and checkout validation
- Checkout UI extensions, admin actions and blocks, and theme app extensions
- Embedded admin interface built with App Bridge and Polaris web components
- App Store submission package for public apps: listing copy, screenshots, billing setup and compliance webhooks
- Repository, hosting and Partner organization ownership in your name, with a release runbook
FAQ
Common questions
What is the difference between a custom app and a public Shopify app?
A custom app runs on your own store or the stores in one Plus organization, and it does not go through App Store review. A public app can install on any merchant's store, lists in the Shopify App Store and must pass Shopify's review. Shopify does not let you change the distribution method later, so pick based on who will use the app.
When is building a Shopify app the wrong choice?
Building is the wrong choice if an App Store app covers the need at a fee you accept, if Shopify Flow can automate it, or if a theme edit solves it. A custom app also carries upkeep, because Shopify releases new API versions each quarter and retires old ones. We raise these alternatives on the first call.
Do we need Shopify Plus?
It depends on the extension. Shopify restricts custom apps that contain Functions, and checkout UI extensions on the information, shipping and payment steps, to Plus stores. Admin extensions, webhooks, app proxies, theme app extensions and thank-you page extensions work on other plans. Shopify adjusts these rules, so we confirm them against its documentation during discovery.
Who owns the app, the code and the merchant data?
You do. The repository, the hosting account, the database and the app record in the Partner organization sit in your name, and devinsta works as a collaborator you can remove. For public apps the App Store listing and the merchant relationships belong to you as well.