Custom Shopify App Development
Custom or public apps, Functions and checkout extensions.
Custom or public app, Shopify Functions, checkout and theme extensions, GraphQL integrations: we write the scope with you and quote a fixed price. Git repository and source code handed over.
Shopify cannot be modified the way PrestaShop or WooCommerce can: no access to core code, no database to extend. Everything goes through apps, extensions and Functions, within a framework set by Shopify. It is a constraint, but also a guarantee: a well-built app does not break when Shopify updates the platform. We build custom Shopify apps inside that framework, with a written scope and a fixed price agreed before we start.
Custom app or public app
| Format | Who it is for |
|---|---|
| Custom app (private) | Your store only, installed directly without going through the App Store. Ideal for automation, a business-specific admin screen or an integration with your internal tools. |
| Public app | Listed on the App Store for other merchants. It involves billing through the Billing API, an onboarding flow, a listing and Shopify’s app review. |
What we build on Shopify
Shopify Functions
Business logic executed by Shopify at cart and checkout time: custom discounts, hiding or renaming delivery and payment methods, cart validation, line bundling. Functions replace the former Shopify Scripts and work on every compatible plan, not only Shopify Plus.
Checkout extensions
Fields and blocks in the checkout, the thank-you page and the order status page, through Checkout UI Extensions. If your customisations still relied on checkout.liquid or additional scripts, we inventory them and rebuild them in this model.
Theme app extensions
App blocks added to the theme without touching its code, placed by the merchant in the theme editor. The theme can be updated without losing the feature.
Admin and integrations
Screens embedded in the Shopify admin, sync with an ERP, a PIM, a 3PL or an invoicing tool through the GraphQL Admin API, webhooks and bulk operations for large catalogues. Metafields and metaobjects structure the data specific to your business.
How we write a Shopify app
- Shopify’s official template (React Router, formerly Remix) and Shopify CLI, to follow platform changes without rewrites.
- GraphQL Admin API with an explicit API version and a plan to upgrade it every quarter.
- Verified, idempotent webhooks: the same event received twice never triggers two jobs.
- GDPR compliance webhooks implemented, mandatory for public apps and recommended for custom ones.
- Polaris interface in the admin, so the app looks like the rest of Shopify.
What you receive at delivery
- The app deployed and installed on your store, with its Git repository.
- The complete source code with no restrictive licence.
- Operations documentation: hosting, environment variables, deployment.
- 12 months of compatibility updates, including Shopify API version upgrades.
What drives the price of a Shopify app
A custom app starts at €4,000. A public App Store app usually lands between €15,000 and €50,000 depending on scope.
| Factor | Effect on the quote |
|---|---|
| Format | A custom app avoids billing, onboarding and App Store review. |
| Extension points | A single Function is quick; an app combining Functions, checkout extensions and admin screens takes longer. |
| Integrations | A documented API, or high-volume sync with bulk operations and retries. |
| Hosting | The app needs a server; we set it up or deploy on your infrastructure. |
Shopify, PrestaShop or WooCommerce?
If your need requires changing the store core or storing complex data, an open-source platform may fit better. We compare the options on our PrestaShop vs Shopify and WooCommerce vs Shopify pages, and also handle Shopify to WooCommerce migration. For automation and AI on Shopify, see Shopify automation and AI.
How we can help
Custom app
Automation, admin screens and integrations for your store only.
Public app
Billing, onboarding, App Store listing and Shopify review.
Shopify Functions
Discounts, delivery, payment and cart validation executed by Shopify.
Checkout extensions
Fields and blocks in checkout, thank-you and order status pages.
Theme app extensions
App blocks the merchant places in the theme editor.
Integrations
ERP, PIM, 3PL: GraphQL Admin API, webhooks, bulk operations.
How we work
-
01
Scoping
A 20-minute call, custom or public app decision, then a written scope.
-
02
Fixed quote within 24 h
Fixed price, committed timeline, hosting cost stated.
-
03
Development and testing
Built on a development store, then tested on yours.
-
04
Delivery and support
Deployment, Git repository, documentation and 12 months of updates.
Tech stack
Ready when you are.
No pitch — just an honest assessment of your project in 20 minutes.
Frequently asked questions
How much does a custom Shopify app cost?
A custom app for your store alone starts at €4,000 and is delivered in three to six weeks. A public App Store app, with billing, onboarding and Shopify review, usually lands between €15,000 and €50,000. The quote is fixed once the scope is approved.
Custom app or public app: what is the difference?
A custom app is installed only on your store, with no public listing or review. A public app is listed on the App Store and can be installed by any merchant; it must handle billing and pass Shopify's review.
What are Shopify Functions for?
They are functions executed by Shopify at cart and checkout time to apply your logic: discounts, delivery, payment, validation. They replace the former Shopify Scripts.
Can you migrate my checkout customisations?
Yes. We inventory existing customisations (checkout.liquid, additional scripts, Shopify Scripts) and rebuild them with Checkout UI Extensions and Functions.
Do I own the source code?
Yes. You receive the full Git repository and deployment documentation, with no blocking clause.
Does the app need hosting?
Yes, an app needs a server for its admin interface and webhooks. We set up hosting or deploy on your infrastructure; the monthly cost is stated in the quote.