checkout ui extensions
Fields, banners, upsells, gift options and validations inside checkout, plus the thank-you and order status pages. Configured in the checkout editor, no theme code.
$ storesmith build --apps
custom apps for the logic your store actually runs on.
StoreSmith builds custom Shopify apps for Shopify Plus merchants: private apps for one Plus org and public apps through App Store review. Checkout extensions, Shopify Functions, admin tooling and the backend that ties them together. Written against a spec, reviewed and signed by a senior engineer.
01 — what we build
extensions, functions and the app behind them.
Most custom work on Plus is a mix of these. We pick the surface Shopify supports for the job, so the app survives the next platform release.
shopify functions
Discount rules, delivery and payment customisations, cart and checkout validation, bundles via cart transforms. Your business rules, run by Shopify inside checkout.
admin apps & extensions
Embedded admin screens, actions and blocks on orders, products and customers. The tool your team needs, in the admin they already use.
custom data models
Metafields and metaobjects with proper definitions, so custom data is typed, editable in the admin and readable by themes, Functions and the Storefront API.
theme app extensions
App blocks and embeds merchants place in the theme editor. Nothing injected into theme files, nothing left behind on uninstall.
public apps & app store review
Billing API, OAuth and scopes, mandatory privacy webhooks, listing and review. The team has taken a dozen-plus apps through it.
02 — typical architecture
logic runs where shopify runs it.
Rules that must hold at checkout live in Functions. Data lives in metafields. The app backend handles what Shopify can't: syncing, scheduling and talking to your other systems.
- storefront · checkouttheme app blocks and checkout ui extensions collect and show data
- functionsdiscount, delivery, payment and validation rules run inside checkout
- app backendadmin graphql api, webhooks, queued jobs and retries
- your systemserp, crm, pos or 3pl, connected through the backend
✓ platform surfaces first
If an extension point or Function covers it, we use it. Fewer script hacks means fewer surprises when Shopify ships a change.
✓ versioned api calls
Each app pins an API version. We read every release and move the app forward before an old version is retired.
✓ minimum scopes
The app asks for the access it needs and nothing else. Customer data stays scoped and erasable.
03 — when it's right
a custom app, or something off the shelf?
If a well-supported app on the App Store does the job, we'll say so. Custom is worth it when the logic is yours.
- a good fit
- Checkout or pricing rules no public app models correctly. Admin workflows your team does by hand. Several stores or brands that need the same logic. An internal tool you want to own, not rent.
- needs shopify plus
- Checkout UI extensions in the information, shipping and payment steps, and Functions shipped in a custom app, are Plus features. We'll tell you what applies to your plan at scoping.
- not our focus
- Template store setups and theme reskins. If that's what you need, we'll point you to someone good.
- how it's priced
- Build sprints, quoted after scoping. A retainer if you want the app kept current with each Shopify release. See pricing.
04 — proof
custom logic we've shipped. names withheld.
Work is listed by industry and pattern, with figures rounded. Our own apps are built on the same signed pipeline.
fashion wearables · integrated high-ticket
2–4×online AOV vs. category norm
First online channel for a multi-brand watch-and-jewellery retailer — store inventory, CRM and an authentication trust layer wired into a high-ticket checkout.
read the use case →wholesale distribution · b2b automation
<3min per wholesale order
Several legacy storefronts merged into one Shopify Plus store, with automated wholesale price tiers by customer segment and real-time inventory sync.
read the use case →our own apps, same pipeline.
Date picker, store locator, crm connect and more — each one started as a problem we kept solving by hand.
05 — questions
common questions.
should i build a custom shopify app or use one from the app store?
If a well-supported App Store app does the job, use it. Custom is worth it when the logic is yours: checkout or pricing rules no public app models correctly, admin workflows your team does by hand, several stores or brands that need the same logic, or an internal tool you want to own rather than rent.
shopify functions or an app: which should run my logic?
Rules that must hold at checkout (discounts, delivery and payment customisations, cart and checkout validation) belong in Shopify Functions. The app backend handles what Shopify can't: syncing, scheduling and talking to your other systems. Custom data lives in metafields and metaobjects.
which custom app features need shopify plus?
Checkout UI extensions in the information, shipping and payment steps, and Functions shipped in a custom app, are Shopify Plus features. We confirm what applies to your plan at scoping.
can you take a public app through shopify app store review?
Yes. That covers the Billing API, OAuth and scopes, mandatory privacy webhooks, the listing and the review. The team has taken a dozen-plus apps through it.
how is a custom app priced?
In one-week build sprints, quoted after scoping, with a fixed price per sprint you approve before work starts. A retainer keeps the app current with each Shopify release if you want it. See pricing.
06 — start
tell us the rule your store can't express.
An engineer replies with what we'd build, which Shopify surfaces it would use, how long and roughly what it costs.