Custom Shopify App Development in India

Description

Service Custom Shopify app development

A custom Shopify app is software built for one store instead of for the App Store. It suits rules and data flows that are specific to your business: syncing orders to an ERP, enforcing your own discount or payment logic, or adding a tool for staff inside the admin. WavX checks first whether an existing app already does the job, then scopes and quotes.

Discuss a Shopify requirement Last updated 2 October 2026

What a custom app is

Shopify apps are distributed in one of two ways, and the choice decides almost everything that follows.

Public app

Custom app

Who can install it

Any store, through the Shopify App Store

One store, or several stores in the same Plus organisation

Shopify review before launch

Yes

No

Can charge through Shopify's app billing

Usual owner

A software company selling to many merchants

The merchant

Shopify does not allow the distribution method to be changed once it is selected, so this is settled at the start. "Private app" is the older name for the same idea: Shopify announced in January 2022 that private apps would be replaced by custom apps. As of October 2026, custom apps are created and managed in Shopify's Dev Dashboard. Apps created inside the Shopify admin before 1 January 2026 are treated as legacy custom apps, and that route is closed for new ones.

WavX builds custom apps for a merchant's own store. The app is created in the merchant's Shopify organisation, its backend runs in a cloud account in the merchant's name, and the source code belongs to the merchant.

What merchants ask for, and how each is built

A request usually falls into one of four kinds of work: a theme change, an existing App Store app, a Shopify Function, or an integration through the Admin API. Only the last two need a custom app. This table describes how each request is built on Shopify's platform; it is not a list of past projects.

Request

How it is built

Shopify pieces used

Send every order to Tally, Zoho or an ERP

A backend app listens for order webhooks , writes to the other system, and reconciles on a schedule

Webhooks, GraphQL Admin API

Keep Shopify stock in step with a warehouse system

A scheduled job reads stock from the source and updates inventory in Shopify

GraphQL Admin API, bulk operations for large catalogues

Discount rules Shopify's settings cannot express

A Discount Function holding the rule, configured from an admin screen

Shopify Functions

Hide cash on delivery above an order value or for some pin codes

A Payment Customization Function

Stop checkout when an order breaks a rule (minimum quantity, restricted address)

A Cart and Checkout Validation Function

A screen for staff inside the Shopify admin (approve wholesale orders, print a GST invoice)

An embedded app page, with admin action or block extensions on the order page

App Home, admin UI extensions

A storefront widget fed by your own data (delivery estimate by pin code, store locator)

A theme app extension for the display, an app proxy to fetch the data

Theme app extensions, app proxies

An extra field or message in checkout

A checkout UI extension

Checkout UI extensions

Tag orders or notify staff when something happens in the store

Usually no app at all: a Shopify Flow workflow

Shopify Flow

The Shopify Admin API integration page covers the data side in more detail, and custom Shopify features covers requests that turn out not to need an app.

What your plan allows

The same app can be possible on one plan and blocked on another. These are the rules as of October 2026.

Capability

Basic, Grow, Advanced

Plus

Custom app using the Admin API and webhooks

Custom app containing Shopify Functions

No. Functions must come from a public App Store app

Checkout UI extensions on the information, shipping and payment steps

Eligible apps on the Thank you and Order status pages

One custom app installed across several stores

No, single store

Yes, within one Plus organisation

GraphQL Admin API rate limit

100 points per second (200 on Advanced)

1,000 points per second

The second row is the one that surprises merchants. A store on Grow that wants its own discount logic at checkout cannot get it from a custom app. The choices are an App Store app that already contains a suitable Function, a rule applied before checkout in the cart, or a move to Plus. Shopify's help centre also states that a store must be on the Grow plan or higher to use custom apps with access to level 2 customer data, which Shopify defines as name, address, phone and email. If your store is on Basic, confirm this before commissioning an app that needs customer details.

How WavX builds a custom app

Write the rule down. One sentence per behaviour: "orders above ₹5,000 to pin codes on this list cannot use cash on delivery". If the rule cannot be written plainly, it is not ready to build.

Check what already exists. A Shopify setting, a Flow workflow or an App Store app may already do it. If one does, WavX says so before quoting.

Decide where the data lives. Shopify separates metafields, which add a field to an existing object such as a product or order, from metaobjects, which are new record types you define. Data that belongs to neither goes in the app's own database.

Build against a dev store. The app is scaffolded with Shopify CLI on Shopify's React Router template and uses the GraphQL Admin API. Shopify has classed the REST Admin API as legacy since 1 October 2024 and has required new public apps to use GraphQL since 1 April 2025, so new work should not start on REST.

Handle webhooks defensively. Shopify expects a response within five seconds and retries a failed delivery up to eight times over four hours; if failures persist, the subscription is removed. It does not promise ordering, and the same event can arrive twice. The app therefore verifies each message's signature, ignores duplicates using the webhook ID, queues the work, and runs a scheduled check against the API to catch anything missed.

Deploy and hand over. The backend is hosted in the merchant's cloud account. The handover includes the repository, a description of how to deploy, and a list of the API version and scopes the app uses.

Limits to know before commissioning one

Functions run inside Shopify, within fixed budgets. For carts of up to 200 line items, a Function gets 11 million instructions, 128 kB of input and 20 kB of output, and the compiled module cannot exceed 256 kB. Network access from a Function has to be enabled by Shopify and, for most Function types, is documented only for enterprise stores with custom apps. A rule that needs a live lookup from your server at checkout is usually redesigned so the data is synced into metafields beforehand.

A store can run a limited number of Functions. Shopify allows at most 25 active discount Functions, 25 payment customisation Functions and 25 validation Functions on a store. Discount Functions run at the same time and know nothing about each other.

Checkout UI extensions cannot touch the page itself. They run in an isolated sandbox, use only the components Shopify provides, and have no access to payment details or checkout HTML.

API calls are metered. A single GraphQL query cannot cost more than 1,000 points on any plan. Reading a whole catalogue is done with bulk operations, which return a JSONL file and are not charged against the normal limit.

API versions expire. Shopify releases a version every quarter and supports each for a minimum of twelve months. A request to a version that is no longer available is answered with the oldest one that is, which may behave differently.

An app is a running service. It has a hosting bill, logs that someone must read, and credentials that must be rotated when people leave.

When an App Store app is the right answer

Often. A custom app is the wrong purchase when:

The need is common. Reviews, product filters, fixed bundles and shipping labels are solved problems. Shopify's own Bundles app (fixed bundles and multipacks) and Search & Discovery app (filters, synonyms, recommendations) are both listed as free as of October 2026.

Your store is not on Plus and the logic must run at checkout. A public app containing a Function is then the only route Shopify allows.

The rule may change next quarter. A subscription to an app can be cancelled. A custom app is a commitment to maintain it.

Flow can do it. Shopify Flow is a free app on Basic, Grow, Advanced and Plus. Its "Send HTTP request" action, which lets a workflow call another system, is available on Grow and above.

A custom app earns its cost when the rule is specific to your business, when the data has to reach a system no App Store app connects to, or when several overlapping apps are being paid for monthly to approximate one behaviour. The comparison of a custom app against an App Store app works through the arithmetic.

Cost and timeline

WavX does not publish a fixed price for Shopify app work; it is quoted after scoping. The number depends mostly on how many outside systems the app talks to, whether any of it runs at checkout, and whether staff need their own screens. The Shopify app development cost guide explains each driver. Engagements can be fixed price, time and materials, or a mix of the two.

If the requirement is a single feature and you are not yet sure it needs an app, describe it on the custom requirements page and WavX will say which of the four kinds of work it is. Custom apps are one part of Shopify development at WavX.

Frequently asked questions

What is the difference between a custom app and a public Shopify app?

A public app is listed for any store to install and must pass Shopify's review. A custom app is built for a single store, or for the stores in one Plus organisation, and needs no review. A custom app cannot charge through Shopify's app billing, which does not matter when the merchant owns it.

Is a private app the same as a custom app?

For practical purposes, yes. Private app is the older name. Shopify announced in January 2022 that private apps would be replaced by custom apps, and its documentation now uses only the newer term.

Can a custom app change my checkout or discounts?

On Shopify Plus, yes: a custom app can contain Shopify Functions and checkout UI extensions. On Basic, Grow and Advanced, Shopify only allows Functions that arrive inside a public app from the App Store, so custom discount or payment logic has to come from an existing app or be handled outside checkout.

Who owns the app after it is built?

You do. WavX hands over the source code and the intellectual property for what it ships, and the app is created in your Shopify organisation and hosted in an account in your company's name.

How much does a custom Shopify app cost?

It is quoted after scoping, because the cost depends on how many systems the app talks to and how much of it runs at checkout. We do not publish a fixed figure for Shopify app work. Our Shopify app development cost guide explains what drives the number.

Does a custom app need maintenance?

Yes. Shopify releases a new API version every three months and supports each one for at least twelve months, so an app that is never updated will eventually be answered with a newer version than it was written for. Plan for at least one update a year, plus hosting.

Sources

Shopify developer docs: About app distribution · read 2 October 2026

Shopify Help Center: Custom apps · read 2 October 2026

Shopify changelog: Introducing a new custom app experience (24 January 2022) · read 2 October 2026

Shopify developer docs: About Shopify Functions · read 2 October 2026

Shopify developer docs: Function APIs reference and limits · read 2 October 2026

Shopify developer docs: Network access for Shopify Functions · read 2 October 2026

Shopify developer docs: Checkout UI extensions · read 2 October 2026

Shopify Help Center: Customising checkout · read 2 October 2026

Shopify developer docs: GraphQL Admin API rate limits · read 2 October 2026

Shopify developer docs: REST Admin API reference (legacy notice) · read 2 October 2026

Shopify developer docs: API versioning · read 2 October 2026

Shopify developer docs: Troubleshooting webhooks · read 2 October 2026

Shopify developer docs: About webhooks · read 2 October 2026

Shopify developer docs: Scaffold an app · read 2 October 2026

Shopify developer docs: Custom data (metafields and metaobjects) · read 2 October 2026

Shopify developer docs: Bulk operation queries · read 2 October 2026

Shopify developer docs: Theme app extensions · read 2 October 2026

Shopify developer docs: App proxies · read 2 October 2026

Shopify Help Center: Shopify Flow · read 2 October 2026

Shopify App Store: Shopify Bundles · read 2 October 2026

Shopify App Store: Shopify Search & Discovery · read 2 October 2026

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