SERVICES  /  APP DEVELOPMENT

Custom Shopify apps. Functions-ready.

Shopify app development for UK brands — public and private apps, Scripts → Functions migrations, AI integrations (OpenAI, Claude, Gemini). Built on TypeScript, Node, and GraphQL Admin.

FROM £2,999
TIMELINE 2–8 wks
APPS SHIPPED 60+
STACK Node · TS · GraphQL
TEAM 1–2 srs + PM
Get an app quote
§ STACK — WHAT YOUR APP IS BUILT ON
SHOPIFY · TYPESCRIPT · NODE · GRAPHQL · VERCEL
SHOPIFY
ADMIN · FUNCTIONS
TYPESCRIPT
STRICT · TYPED
NODE.JS
RUNTIME · BACKEND
GRAPHQL
ADMIN API
VERCEL
HOSTING · EDGE

BRAND MARKS © THEIR RESPECTIVE OWNERS · POLARIS + APP BRIDGE FOR EMBEDDED ADMIN UIS · ALSO FLY.IO, RAILWAY, HEROKU AS HOSTING ALTERNATIVES.

§ 01
Why now

Shopify Scripts are being deprecated. Functions is mandatory.

You have Scripts running in checkout.

Discounts, shipping, payments, line items — all moving to Functions. The deprecation timer is on. We migrate them safely.

Your customer account pages are still legacy Liquid.

Shopify's new extensible Customer Accounts (with the Customer Account API) replace the old /account templates — order tracking, returns portals, B2B re-orders, loyalty UI all live here now.

You need bundles, build-a-box, or grouped products.

Native Shopify Bundles plus the Cart Transform Function API replace third-party bundle apps. Faster, cheaper, and survives theme upgrades.

Your integrations have outgrown no-code tools.

Two-way sync at BFCM-scale needs queues, retries, idempotency, and observability. We pair custom apps with Shopify Flow custom triggers/actions for the automations that don't need code.

Your custom app is on a deprecated API version.

Admin REST is being phased out for many endpoints. We lift apps to GraphQL Admin and current API versions.

You need a private admin tool merchants love.

Embedded admin UI on Polaris. Merchants stay in Shopify, your app does the work — no separate dashboard to log into.

§ 02
Process

Spec to shipped app.

WK 01

Spec + API audit

Existing Scripts/apps audited. Functions equivalents mapped. API surface area drawn.

WK 01–02

Architecture

GraphQL queries planned. Webhook topology. Queue + retry strategy. Hosting choice (Vercel/Fly/Heroku).

WK 02–04

Build + UAT

Functions / app built incrementally. Merchant tests every Friday. Scripts disabled tier-by-tier.

WK 04–05

Go-live + 30-day support

Cutover off-peak. Live monitoring for 14 days. 30-day fix window included.

§ 03
Deliverables

What ships, specifically.

App / Functions source

In your GitHub. CI/CD wired to Vercel or your infra of choice.

API documentation

Endpoints, payloads, retries — everything a future dev needs to extend it.

Webhook + queue layer

Idempotent, observable, with dead-letter handling.

Embedded admin UI (where relevant)

Polaris + App Bridge. Looks native. Loads fast.

Customer Account UI Extensions (optional)

Order tracking, returns, B2B re-orders, loyalty — built on the new extensible accounts surface.

Cart Transform / Bundles support

Native Shopify Bundles configured + Cart Transform Function for build-a-box logic where it applies.

Shopify Flow custom triggers/actions

Automations exposed to merchants in Flow — fraud rules, tag-on-event, fulfilment exceptions.

UAT scripts

Reproducible test cases for every discount/shipping/payment/cart scenario.

30-day post-launch support

Bug fixes and config tweaks included.

§ 04
Pricing

Three app tiers.

FUNCTIONS SPRINT
£2,999
2–3 WKS

Migrate Scripts to Functions. Discounts, shipping, payments, Cart Transform for Bundles.

  • Up to 5 Functions
  • Scripts → Functions migration
  • Cart Transform (Bundles)
  • Checkout Extensibility
  • UAT + 14-day post-launch
Get this tier
CUSTOM APP · MOST POPULAR
£8,999
4–6 WKS

Bespoke private app. Embedded admin UI plus optional Customer Account UI Extensions.

  • Public or private app
  • Embedded admin UI (Polaris)
  • Customer Account UI Extensions
  • Webhooks + GraphQL Admin
  • OAuth + billing + hosted infra
Get this tier
INTEGRATIONS
£4,999
3–5 WKS

Two-way sync with ERP / PIM / CRM / 3PL plus Shopify Flow automations. Idempotent, observable, GDPR-compliant.

  • ERP / PIM / 3PL sync
  • Custom Shopify Flow triggers + actions
  • Webhook + queue layer
  • Reconciliation dashboard
  • GDPR DPA
Get this tier
§ 06
FAQ

App + Functions questions.

When do Shopify Scripts actually stop working? +

Shopify has staged deprecation in motion across 2025–2026, with different Script types retiring on different dates. We can audit your existing Scripts and tell you the exact deadline for each one before quoting a Functions migration.

Do I need Shopify Plus to use Functions? +

No. Shopify Functions are available on all Shopify plans, including Basic, Shopify, and Advanced. Shopify Scripts (the legacy thing being deprecated) were Plus-only — Functions are democratising that capability across all tiers.

Should I build a public Shopify app or a private app? +

It depends on whether you intend to sell or distribute it. We build both. Private apps are faster (no review queue, no billing infrastructure) and are best for your-store-only logic. Public apps go in the Shopify App Store with Shopify-hosted billing — better when distributing to other merchants.

What technology stack do you use for Shopify app development? +

TypeScript + Node + GraphQL Admin API as standard. Apps are hosted on Vercel by default, or your hosting choice (Fly.io, Railway, Heroku, or your own infrastructure). Polaris + App Bridge for embedded admin UIs. Webhooks + queues for reliability.

Will my custom Shopify app survive an API version bump? +

Yes. We pin to specific API versions and write upgrade tests for each release. Annual API version migration is part of every maintenance retainer — apps stay on supported versions automatically rather than breaking when Shopify deprecates an endpoint.

How long does a custom Shopify app take to build? +

Functions Sprint: 2–3 weeks (£2,999). Custom App: 4–6 weeks (£8,999). Integrations layer: 3–5 weeks (£4,999). Public App Store apps: 6–10 weeks plus Shopify review time. We quote fixed-price after a 30-minute scoping call.

Can you migrate Shopify Scripts to Shopify Functions? +

Yes — that is the Functions Sprint tier. We map your existing Scripts (Discounts, Shipping, Payments, Line Items) to the equivalent Function types, build them, run UAT in parallel with the legacy Scripts, then cut over off-peak. Most stores migrate 5 Scripts in 2–3 weeks.

Do you handle ERP, PIM, or 3PL integrations as Shopify apps? +

Yes — that is the Integrations tier (£4,999). Two-way sync with NetSuite, Linnworks, Cin7, Brightpearl, Unleashed, and most major ERP/PIM/3PL systems. Idempotent webhook handlers, queue-based reliability, reconciliation dashboards.

Can you submit my Shopify app to the Shopify App Store? +

Yes. We handle the full submission process — Polaris admin UI compliance, App Bridge integration, OAuth flow, billing API, GDPR + DPA compliance, and the listing copy. App Store review typically takes 2–6 weeks; we factor that into the launch timeline.

Can you build Customer Account UI Extensions? +

Yes. Shopify's new extensible Customer Accounts replaced the legacy Liquid /account templates — we build custom UI Extensions for order tracking, returns portals, B2B re-orders, subscription self-service, and loyalty dashboards. Pairs naturally with the Custom App tier or sits inside an existing app.

Do you build with Shopify Bundles and the Cart Transform Function? +

Yes. Native Shopify Bundles cover fixed and multipack bundles out of the box; Cart Transform Functions cover anything more complex (build-a-box, dynamic pricing groups, sample bundles). We migrate stores off third-party bundle apps as part of Functions Sprints — typically faster and £200+/month cheaper.

Can you write custom Shopify Flow triggers and actions? +

Yes. Custom Flow triggers (events your app emits) and actions (operations your app performs) let merchants stitch your custom logic into automated workflows alongside native Shopify events. Common use cases: fraud-score tagging, ERP fulfilment exceptions, conditional Klaviyo handoffs.

§ 07 — START YOUR APP

Spec your app.
Ship it in weeks.

Send your brief — we'll come back with an architecture sketch and a fixed quote inside 48 hours.

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