Custom Shopify App Development · Public, custom & checkout apps
Custom Shopify App Development That Ships to Production
Hexanova is a custom Shopify app development company building public App Store apps, private and custom merchant apps, checkout UI extensions, and Shopify Functions. Embedded Remix + Polaris builds, GraphQL Admin API, and app review support with clear scope and weekly demos.
Most Shopify apps do not fail in the code editor. They fail in review queues, at 500-webhook-per-minute spikes, or three months later when a merchant with 80,000 variants installs and the sync falls over. Hexanova builds custom Shopify apps that survive all three: embedded Remix and Polaris admin surfaces, GraphQL Admin API integrations that respect rate limits, billing that reconciles, and a submission package that passes Shopify's app review without a month of round-trips.
The App Store solves 80% of your problem. The other 20% is where the money is.
Every merchant hits the same wall. The pricing rule your sales team actually uses is not in any listing. Your ERP and Shopify disagree on stock by lunchtime. The checkout logic you relied on for years left with checkout.liquid. So you stack four apps that half-work, fight each other, and bill you monthly forever.
A custom Shopify app closes that gap once. Hexanova builds it on Shopify’s own recommended stack, hands you the source code, and gets out of the way, so the logic that differentiates your business finally lives inside the platform running it.
Custom Shopify app development services
Four engagements cover almost every brief we take: a public app for the App Store, a custom app for one merchant, checkout and Functions work, or rescuing an app someone else started.
Built for the App Store listing
Public Shopify App Development
Full Shopify app development services for software teams launching a commercial app: OAuth install flow, embedded admin, managed pricing and the Billing API, mandatory compliance webhooks, and a listing package that clears app review the first or second time, not the fifth.
- OAuth, session tokens, and embedded App Bridge setup
- Recurring or usage-based billing with real reconciliation
- GDPR / mandatory compliance webhook handlers
- Listing copy, screenshots, and review submission support
One merchant, one exact workflow
Custom & Private Merchant Apps
Custom Shopify app development for a single store or Plus org that has outgrown the app ecosystem. When no listing does what your ops team needs, we build the app that does, installed directly to your store with scoped access tokens and no per-seat tax forever.
- Custom app installed via the Shopify admin, no listing required
- ERP, WMS, 3PL, and accounting integrations
- Ops dashboards for merchandising, pricing, and fulfilment
- Source code ownership and deployment handoff
Post-checkout.liquid, done properly
Checkout Extensibility & Shopify Functions
Checkout UI extensions, discount and delivery customisation Functions, cart transforms, and post-purchase surfaces for Plus merchants who lost checkout.liquid and need that logic back, running on Shopify's own infrastructure instead of a fragile script.
- Checkout UI extensions for upsells, fields, and validation
- Discount, delivery, and payment customisation Functions
- Cart transform and bundling logic
- Post-purchase and Thank You page extensions
Inherit it, stabilise it, ship it
App Rescue, Migration & Maintenance
You have an app that a previous agency or freelancer left half-finished, still on REST, or failing review. We audit it, migrate the API surface, fix the webhook and rate-limit failures, and take it to a state where new features are cheap again.
- REST to GraphQL Admin API migration
- Rate limit, retry, and webhook reliability fixes
- App review rejection remediation
- Ongoing maintenance against Shopify API version releases
What we build inside Shopify
“Shopify app” covers six quite different surfaces. Picking the wrong one is the most expensive mistake in a build, so scoping starts here.
Embedded admin apps
Apps that live inside the Shopify admin using App Bridge and Polaris, so merchants never feel like they left the platform. Session token auth, native navigation, and a UI that matches the admin your merchant already knows.
Best for: Merchandising tools, ops consoles, bulk editors
Storefront & theme app extensions
App blocks and app embeds that merchants drop into any Online Store 2.0 theme from the theme editor, with no code edits and nothing left behind when the app is uninstalled.
Best for: Reviews, badges, upsell widgets, size guides
Checkout UI extensions
Native checkout surfaces for Plus merchants: custom fields, upsells, trust content, and validation running inside Shopify's checkout rather than injected scripts that break on every update.
Best for: Plus merchants replacing checkout.liquid logic
Shopify Functions
Server-side business logic compiled to WebAssembly and executed by Shopify: custom discounts, delivery and payment method rules, cart transforms, and bundle pricing that runs at checkout speed.
Best for: Complex discounting, B2B pricing, bundles
Integration & sync apps
Apps that keep Shopify in step with the systems that actually run the business: ERPs, WMS and 3PL platforms, accounting stacks, PIMs, and marketplaces. Built with bulk operations, idempotency, and dead-letter handling.
Best for: Multi-system merchants, high SKU counts
Headless & Hydrogen builds
Storefront API and Hydrogen work when the front end needs to move independently of the admin, paired with the custom app that powers its data and business rules.
Best for: Custom storefronts, multi-brand, content-heavy commerce
Who a custom Shopify app is actually worth it for
Custom app development beats a subscription when the workflow is specific, the app spend is already high, or the logic sits at checkout. When it does not, we will tell you.
Merchants who outgrew the App Store
You are paying four apps to half-solve one workflow, and they conflict with each other. A custom Shopify app costs less over two years and does exactly one job correctly.
Plus merchants after checkout.liquid
Checkout customisations that used to be a Liquid edit now need extensions and Functions. You need someone who has actually shipped both, not someone reading the docs alongside you.
Software teams launching a listing
You have the commercial thesis and the merchant demand, and you need an app development partner to build the product and get it through review while you sell.
Ops teams stitching Shopify to an ERP
Orders, inventory, and fulfilment live in three systems that disagree by lunchtime. We build the sync layer with idempotency and exception visibility.
Not a fit
- ×Theme-only tweaks with no app or data layer
- ×Copies of an existing App Store listing with no differentiation
- ×Anything that requires scraping or violating Shopify's API terms
- ×Projects with no merchant or decision-maker available for review
Shopify app development by merchant type
The right app depends less on your industry label than on your catalogue shape, fulfilment model, and where the margin leaks. These are the patterns we see most.
Fashion & apparel
High variant counts, seasonal drops, and returns rates that make or break margin. Shopify app development for brands that need merchandising and sizing logic the theme cannot express.
- →Size and fit recommendation surfaces
- →Bulk variant and price editors
- →Preorder and drop scheduling
- →Returns and exchange workflows
Health, beauty & supplements
Subscription-heavy catalogues with compliance constraints on claims, shipping, and regional availability. We build the rules into the app instead of a spreadsheet.
- →Subscription and replenishment logic
- →Region-restricted product gating
- →Bundle and kit pricing via Functions
- →Loyalty and referral integrations
B2B & wholesale
Custom Shopify app development for B2B and wholesale operators who need company-level pricing, quotes, credit terms, and reorder flows that Shopify B2B alone does not cover.
- →Customer-specific price lists
- →Quote request and approval flows
- →Net terms and credit limit checks
- →Fast reorder and CSV order upload
Food, beverage & grocery
Delivery windows, perishability, and local fulfilment rules that generic delivery apps handle badly. Delivery customisation Functions fix most of it.
- →Delivery slot and zone rules
- →Minimum basket and surcharge logic
- →Local pickup and route grouping
- →Inventory sync with store systems
Electronics & high-consideration retail
Configurable products, warranties, and post-purchase attachments where checkout and cart logic drive real revenue per order.
- →Product configurators and compatibility rules
- →Warranty and protection plan upsells
- →Post-purchase offer extensions
- →Serial number and registration capture
SaaS & app-first companies
Teams whose product is the Shopify app. We build the listing app itself: billing, multi-tenant architecture, onboarding, and the metrics that show activation.
- →Multi-tenant app architecture
- →Billing API and plan management
- →Merchant onboarding and activation flows
- →Usage analytics and churn signals
The stack we build Shopify apps on
Shopify’s own recommended path, not a bespoke framework you would need us to maintain. Your team, or the next one, can pick this up.
App framework
UI & extensions
APIs & data
Infrastructure
How a Shopify app build runs
Five stages from brief to live app, with a demo you can open at the end of every week.
Scope against Shopify's constraints
Before a line of code: which APIs cover the feature, which need a Function, what rate limits apply, and whether it belongs in a public app, a custom app, or an extension. Half of app rework comes from skipping this.
Design the merchant surface
Polaris-native screens so the app looks like part of the admin, with the install-to-first-value path mapped explicitly. Merchants who cannot get value in one session uninstall in week one.
Build in weekly increments
Embedded app, data model, webhooks, and integrations built in focused sprints on a development store you can open any time. Weekly demos, not a reveal at the end.
Harden for real stores
Bulk operation paths for large catalogues, retry and backoff on the Admin API, webhook idempotency, uninstall cleanup, and billing edge cases tested before a merchant finds them.
Submit, launch, and support
Listing assets, review checklist, and submission for public apps; direct install and handoff for custom apps. Then a stabilisation window and an API-version maintenance plan.
Why apps get rejected at review
Nearly every rejection we have seen traces back to four things: incorrect OAuth or session token handling, missing mandatory compliance webhooks, a billing implementation that does not match the listing, or an install flow a reviewer cannot complete without support. Each is cheap to get right during the build and expensive to retrofit under a deadline, so the review checklist runs from week one rather than submission week.
Shopify app development cost & engagement models
Most agencies make you sit through two calls before hearing a number. These are the ranges our Shopify app development projects actually land in, before scoping. Integration count, catalogue size, and checkout involvement move them most.
Focused custom app
$8,000 – $20,000
4 – 7 weeks
A single-purpose custom Shopify app for one merchant: an embedded admin surface, one or two integrations, and the workflow that is currently costing your team hours a week.
- Embedded Remix + Polaris app
- GraphQL Admin API integration
- Webhooks and background jobs
- Deployment and source handoff
Public App Store launch
$20,000 – $60,000
8 – 16 weeks
A commercial Shopify app built for a listing: multi-tenant architecture, Billing API, onboarding, compliance webhooks, and the full app review submission package.
- Multi-tenant app architecture
- Billing plans and reconciliation
- Merchant onboarding and activation
- Listing assets and review submission
Checkout & Functions build
$10,000 – $35,000
5 – 10 weeks
Checkout UI extensions and Shopify Functions for Plus merchants replacing checkout.liquid logic, custom discount engines, or delivery rules that no listed app handles correctly.
- Checkout UI extensions
- Discount / delivery / payment Functions
- Cart transform and bundle logic
- Load testing against peak traffic
Worth doing the arithmetic before you commit: four App Store subscriptions at $99 a month is roughly $4,750 a year, every year, for software you cannot change. A focused custom app is a one-time build you own outright, and it does the job the way your team actually works. Book a scoping call and we will tell you honestly which side of that line your project falls on.
Choosing between Shopify app development companies
Every agency page claims the same things. These are the five factors that actually separate the best agencies for custom Shopify app development from the ones that learn on your budget, and the questions worth asking whoever you shortlist.
| Factor | Freelancers | Theme-first agencies | Hexanova |
|---|---|---|---|
| Shopify-specific depth | Often a generalist learning on your budget | Theme and storefront focus, thinner on apps | App-layer focus: extensions, Functions, Admin API |
| App review outcome | Submission handed back to you | Review support billed separately | Review checklist applied during the build |
| Scale readiness | Works on a dev store, breaks at 50k products | Depends on who is staffed that quarter | Bulk operations and rate-limit strategy from day one |
| Communication | One person, one time zone, no cover | Account layers between you and the engineer | Direct access to the build team, weekly demos |
| After launch | Often unreachable at the next API version | Retainer required before anything is touched | Handoff, stabilisation window, optional maintenance |
Commerce work we have shipped
Multi-vendor marketplaces, ordering flows, and the ops systems behind them. The same problems a Shopify app solves, in projects you can read end to end.
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Shopify app development FAQ
Cost, timelines, app review, and the public-versus-custom decision, answered plainly.
What is custom Shopify app development?
Custom Shopify app development means building an application that extends Shopify with logic the platform and the App Store do not provide: an embedded admin tool, a storefront or checkout extension, a Shopify Function, or a sync layer to another system. It can be a public app listed on the Shopify App Store, or a custom app installed to a single store for one merchant's exact workflow.
How much does Shopify app development cost?
A focused custom app for one merchant typically runs $8,000 to $20,000. A public App Store app with multi-tenant architecture, billing, onboarding, and review submission usually lands between $20,000 and $60,000. Checkout extension and Shopify Functions work sits in the $10,000 to $35,000 range. The variables that move the number most are integration count, catalogue size, and whether checkout or Functions are involved. After a scoping call, Hexanova sends a fixed or phased proposal.
How long does it take to build a Shopify app?
Four to seven weeks for a focused custom app, eight to sixteen weeks for a public App Store launch including review, and five to ten weeks for checkout and Functions work. App review itself adds days to a few weeks depending on how clean the submission is, which is why we apply the review checklist during the build rather than after it.
What is the difference between a public app and a custom app?
A public app is listed on the Shopify App Store, installable by any merchant, and must pass Shopify's app review. A custom app is built for one store or Plus organisation, installed directly from the admin, and skips review entirely. If you are solving your own operational problem, a custom app is faster and cheaper. If you are selling to merchants, you need a public app.
Do you handle the Shopify App Store review process?
Yes. For public apps we build against the review requirements from the start: OAuth and session token handling, mandatory compliance webhooks, billing implementation, performance budgets, and support surfaces. We prepare the listing copy, screenshots, and demo store, submit, and work through any reviewer feedback with you.
Which technologies do you use for Shopify app development?
Remix with TypeScript on Node.js, Shopify App Bridge and Polaris for embedded admin UI, the GraphQL Admin API with bulk operations for data, Shopify Functions in Rust for server-side commerce logic, and checkout UI extensions for checkout surfaces. Data and queueing typically sit on Postgres and Redis, deployed to Vercel, Fly, or AWS depending on your constraints.
Can you work with our existing Shopify app or agency code?
Yes. A meaningful share of our work is app rescue: inheriting a half-finished build, migrating REST calls to the GraphQL Admin API, fixing webhook and rate-limit failures, and remediating app review rejections. We start with a short audit so you get a written picture of the state before committing to a rebuild or a repair.
How do I choose the best agency for custom Shopify app development?
Ask for apps they have shipped and whether those passed review on first or second submission. Ask how they handle Admin API rate limits and stores with large catalogues. Ask what happens at the next API version release. Agencies that only build themes will say yes to app work and learn on your budget, and the gap shows up at scale, not in the demo.
Do you provide support after the Shopify app launches?
Every build ships with a handoff, documentation, and a stabilisation window after launch. Shopify releases a new API version quarterly and deprecates on a schedule, so most clients keep a light maintenance retainer that covers version upgrades, monitoring, and small feature work.
Do you own the code, or do we?
You do. Source code, repositories, and infrastructure are yours, transferred at handoff. We do not hold apps hostage behind a retainer, and we do not resell your build to a competitor.
Tell us what Shopify will not do
Bring the workflow the platform fights you on, or the listing you want to launch. In one call we will tell you whether it needs a public app, a custom app, an extension, or a Function, what it will cost, and how long it takes. If a $20-a-month listing already solves it, we will say so.