I build private Shopify apps: integrations with your ERP or accounting, order and pricing logic your theme can’t handle, Shopify Functions and checkout extensions. One senior developer writes it, and you own the code.
A custom Shopify app is built for one store and installed only there. It works through Shopify’s Admin and Storefront APIs, so it can sync data with your other systems, run order or pricing logic, add checkout extensions and, on Shopify Plus, run Shopify Functions. You pay for it once, and there’s no monthly app fee.
Start with the App Store. If an app does what you need at a price you’re happy to pay every month, install it, and I’ll say so on the first call. A custom app makes sense when:
No app does the job, or the closest one needs workarounds your team has to remember.
You pay for a large app to use one feature, and you’ll be paying for years. An app at ₹2,000 a month costs ₹72,000 over three years.
Your pricing rules, a vendor’s file format or your ERP aren’t in anyone’s off-the-shelf app.
Data has to move between Shopify and a system no app talks to.
A private app with read-only Admin API access and webhooks. It syncs about 2,000 products and 100,000+ orders into its own database for forecasting, margin and vendor reorder sheets.
See the dashboard workA custom print-ordering flow with live pricing rules, tighter cart behaviour and automated invoices for a production-heavy store.
Subscription flows rebuilt on Shopify’s APIs, with private sync workflows, during their Magento to Shopify Plus migration.
My own Claude Code skill that checks a Shopify theme against 80+ rules.
ERP, accounting, inventory, warehouse and marketplace sync through the Admin GraphQL API and webhooks.
Custom pricing, bundles, B2B rules, and “Get a quote” in place of “Add to cart”.
Discount, shipping and payment rules, plus cart and checkout validation.
Additions to the checkout and to its Thank-you and Order status pages.
Bulk editors and internal workflows for your team.
Moving the logic in your Shopify Scripts over to Functions.
Any plan: Admin API integrations, admin tools, and checkout extensions on the Thank-you and Order status pages.
Shopify Plus only: custom apps that use Functions, and checkout extensions inside the information, shipping and payment steps. For that work, see Shopify Plus development.
Moving off Shopify Scripts? Here’s how the Scripts to Functions migration works.
The facts that decide whether a custom app is worth it, and the two options side by side.
is what an app at ₹2,000 a month costs over three years, before you’ve owned any of it.
Shopify releases a new API version, and supports each one for at least 12 months.
Source: Shopify API versioning
for custom apps that use Shopify Functions. Public App Store apps with Functions work on every plan.
Source: Shopify Functions
| App Store app | Custom app | |
|---|---|---|
| How you pay | Monthly fee, often rising with volume | One-time build, optional upkeep |
| Fits your exact logic | Only if someone built it already | Built around it |
| Installed on | Thousands of stores | Your store only |
| Who owns the code | The app developer | You |
| Best for | Common needs at a fair monthly price | Your own logic, systems and workflows |
I map what the app has to do against what Shopify’s APIs allow. You get a written spec and the data map, and the fee is credited to the build if you go ahead.
A fixed price, a timeline and a Definition of Done, agreed before work starts. Most custom app builds take 45 to 60 days. You pay 30% to start, 30% at the agreed milestone and 40% at delivery.
I build and test on a development store first, then install on yours.
The code and IP are assigned to you.
Shopify ships a new API version every quarter and supports each one for at least 12 months. Plan on a check-up at least once a year, inside a retainer or as a small fixed job.
What moves the price: how many systems the app connects, how much logic it carries, whether it needs Functions or checkout extensions, and how much data it moves.
Retainers are 10% off with a 6-month commitment and 20% off with 12 months. No GST is added to any price. Every price I charge is on one pricing page.
A written spec and data map. Credited to the build.
One store’s integration, logic or admin tool
One or two Functions on a Plus store
API updates and new features
“Migrations are where we normally lose money — data loss, broken links, downtime. Tanuj moved us from Magento to Shopify with none of it. He built a redirect map to preserve our SEO, migrated every customer and order record, and rebuilt our subscription flow inside three months. Sales grew after the migration. He is the cool head in a hot mess of a migration.”
A custom app costs ₹80,000 to ₹6,00,000, or $1,600 to $10,000 for international brands. You get a fixed price after a ₹40,000 / $750 scoping sprint, which is credited to the build. A single integration or admin tool sits at the low end. Apps with several systems, Functions or checkout extensions sit higher.
Most App Store apps charge a monthly fee, and many charge more as your plan or order volume grows. A custom app costs more upfront, then you pay only for upkeep. It’s worth it when you’d otherwise pay for years, or when no app does what you need.
Not yet. My app work so far is custom apps for single stores. If you’re building an App Store product, I’m not the right first hire for it today.
Admin API integrations, admin tools, and checkout extensions on the Thank-you and Order status pages work on every plan. Custom apps that use Shopify Functions, and checkout extensions inside the checkout steps, need Shopify Plus.
Often, yes. Send me the app’s name and what you use it for. If a custom version would pay for itself, I’ll show you the numbers. If it wouldn’t, I’ll tell you to keep the app.
Yes. That work runs as a Shopify Functions engagement on Plus, and my guide to the Scripts to Functions migration explains how it works.
Shopify releases a new API version every quarter and supports each for at least 12 months. A custom app needs a check-up at least once a year, which I handle inside a retainer or as a small fixed job.
Most take 45 to 60 days from the agreed scope. Your written scope gives the exact timeline.
You do. The code and IP are assigned to you at handover.
Start a brief with the feature you need and the apps you’ve already tried. I’ll reply within 24 hours and tell you whether to build it or install something.
