ECWEBUK
No. 004 / Shopify appsCambridge · UK
✦ Custom Shopify apps

Shopify
apps, built
to ship.

Custom Shopify app development — public App Store apps, private apps for a single merchant, Shopify Functions and checkout extensions. Built by the maker of four live App Store apps.

Why merchants pick EC Web for Shopify app development

Live apps
04
Avg. rating
5.0
Shopify Partner
2017
Founder-led
1

★ What I build

Surface area
01

Public App Store apps

Built, listed, reviewed and launched on the Shopify App Store. Listing copy, screenshots, billing and review prep all handled.

02

Private & custom apps

Single-merchant apps that solve one specific problem. Distributed via custom-app install link or Shopify Plus org-level install.

03

Checkout UI extensions

Custom checkout fields, validation, banners, address pickers and post-purchase pages. Works on every Shopify checkout including Plus.

04

Shopify Functions

Discounts, shipping, payment customisation, delivery customisation, cart transforms — Rust-compiled, runs at the edge.

05

Admin extensions

Admin blocks, action extensions, custom resource pages and metafield editors that feel native inside Shopify Admin.

06

Webhooks & sync

Idempotent webhook handlers, scheduled jobs, backfill tooling and reconciliation reports that hold up under real load.

07

Admin & Storefront APIs

GraphQL Admin, Storefront and Customer Account APIs. Bulk operations, pagination that doesn't blow up, sensible rate-limit handling.

08

App rescues

Pick up an app another agency started or abandoned. Audit the codebase, document what's there, ship the missing 20%.

₤ Engagements

Four ways to work
Discovery
Free30 min · no slides
Define the problem, not the solution.
  • Written brief within 3 working days
  • Concrete scope + fixed price
  • Honest "don't build this" if it applies
  • No obligation, no follow-up spam
Private app
from £8k3–6 weeks · fixed price
Custom Shopify app for a single merchant.
  • Single-merchant install or Plus org-level
  • Weekly demo videos · shared Linear
  • Definition-of-done in writing
  • 30 days of post-launch fixes included
Public App Store app
from £25k8–12 weeks · fixed price
Marketplace-listed, review-ready.
  • App Store review prep + submission
  • Listing copy, screenshots, billing API
  • Multi-tenant architecture from day one
  • 90 days of post-launch support included
Maintenance
from £2k/ month
Ongoing support for an existing app.
  • Feature work, bug fixes, merchant support
  • Shared Slack · 24-hour response
  • Quarterly architecture review
  • Cancel any time, 30 days notice

◎ Receipts

Four apps · live on the App Store

§ How a build runs

Four steps, no surprises
Day 0
01
Discovery

30 min call to define the problem. I'll often suggest existing apps before recommending a build.

Day 1–3
02
Fixed-price spec

Written proposal in 3 working days. Fixed price, fixed scope, written 'definition of done'.

Week 1–10
03
Build

Weekly demo videos, shared Linear board, direct Slack. You see progress whenever you want.

Ongoing
04
Launch & support

Submitted to the App Store if public. Monitoring, docs, included post-launch fixes. Optional retainer.

⚙ Stack

Boring on purpose

Shopify apps live or die on the platform conventions, so I stay close to whatever Shopify recommends today — Shopify CLI, Polaris, token-exchange auth, GraphQL Admin. Beyond that the stack is chosen to be cheap to operate and easy for the next engineer to read.

RemixNext.jsShopify CLIPolarisHydrogenLiquidShopify Functions (Rust)GraphQL AdminGraphQL StorefrontWebhooksPostgresFly.io
✦ The fine print

Honest about who this is not for.

I’d rather wave you off early than waste your time. If any of these are true, the answer is no — and I’ll usually point you at someone who’s a better fit.

  • ×You want a clone of an existing app to undercut its pricing — Shopify will reject it and so will I.
  • ×You need a 'free, ad-supported' app — the model rarely works on Shopify and I won't pretend otherwise.
  • ×You want me to ship without a written spec — fixed-price means a fixed scope. No spec, no fixed price.

? Frequently asked

8 questions

What's the difference between a public and private Shopify app?

A public app is listed on the Shopify App Store, available to any merchant, and goes through Shopify's app review process. A private app (now usually distributed as a 'custom app') is built for a specific merchant or group and installed via a direct link — no review, no marketplace listing. Public apps need multi-tenant architecture, billing API integration, and review prep, so they cost more and take longer. Private apps can be much leaner.

How long does Shopify App Store review take?

Currently 5–10 business days for a first review, plus revision cycles if Shopify finds issues. The trick is shipping a build that's review-ready on first submission — clear scopes, sensible billing flows, no use of deprecated APIs, no third-party scripts that violate the partner programme. Four App Store apps in, I've learned where reviewers push back, so first-pass approval is the norm.

Do you handle the App Store listing copy and screenshots?

Yes. The £25k+ public-app engagement includes listing copy, in-app screenshots, key-image creation, and the longer-form description. I'll also draft your support docs and onboarding flow. If you want a video walkthrough or a marketing site for the app, those are scoped separately.

What does post-launch support look like?

Public apps include 90 days of post-launch support — Shopify review revisions, bug fixes, merchant onboarding tweaks. Private apps include 30 days. After that, most clients move onto a maintenance retainer (from £2k/mo) which covers ongoing support, feature work, and Shopify platform changes.

Can you build apps specifically for Shopify Plus stores?

Yes. Plus-specific work includes B2B/wholesale apps, multi-store apps, custom checkout extensions (which only Plus stores can install), Shopify Flow connectors, and org-level custom apps. Most Plus-specific apps are private/custom rather than public — the audience is too narrow for the App Store to make sense.

Do you take equity or revenue-share for app ideas?

Generally no. Fixed-price engagements keep incentives clean and let me ship work I'm proud of. If you have a strong app idea but no budget, I'd rather point you at the existing apps that already solve it, or help you scope down to a private MVP first.

Can you take over an existing Shopify app I started elsewhere?

Yes — about a third of the work is rescues. Step one is a paid audit (typically £1,500) where I read the codebase, document what's there, and write up what it would cost to finish, fix, or rewrite. From there it's the standard build process. I don't take rescues without an audit first — too many surprises lurk in old code.

What stack do you use?

Remix or Next.js for the app frontend, Polaris for admin UI, Hydrogen if storefront-rendered, Shopify Functions in Rust where applicable, Postgres for state, Fly.io for hosting. I follow the current Shopify CLI conventions and use whichever auth pattern Shopify recommends today (token-exchange, managed install, etc.). I do not chase tech for its own sake — the stack stays boring on purpose.

→ Start

Got an app in mind?

Tell me what the merchant problem is. I’ll come back with a written brief, a fixed price, and a calendar slot — or a pointer to the existing app that already solves it.

Reply window
< 24h
Weekdays, from one real human.
Available for new builds.