How Much Does a Shopify Custom App Cost to Build?

"How much will a custom Shopify app cost?" is the first question on almost every discovery call. The answer is "it depends" — which is correct but useless. Here is the actual range we quote in April 2026, the variables that move the price, and the scoping questions that will either give you a firm number or tell you the project is not ready to be quoted yet.

The Honest Range

Shopify custom apps in 2026 land in four brackets:

• £4,000-£10,000 — Single-purpose private app. One admin page, one or two webhooks, a small amount of product/order/customer logic. Examples: custom order export, bulk metafield updater, simple pricing calculator, Slack notifier with domain logic.
• £12,000-£30,000 — Private app with real admin UI. Multiple screens, configuration, background sync, a handful of Shopify Functions or checkout extensions. Examples: Year/Make/Model vehicle filtering, B2B quote tool, inventory sync with one ERP.
• £30,000-£80,000 — Internal platform. Deep integration with an ERP or PIM, multi-step workflows, permissioning, audit logging, proper observability. Examples: custom subscription engine, full Shopify-to-NetSuite middleware, multi-brand loyalty backend.
• £80,000-£250,000+ — Public app on the Shopify App Store, or a bespoke platform serving multiple client stores. Billing integration, scaling, security review, store installation lifecycle, documentation, support tooling.

The Six Variables That Actually Move the Price

The Scoping Questions That Produce a Firm Number

Before we quote, we need answers to these. If you cannot answer most of them, the project is a discovery engagement, not a build:

1. What specific merchant action triggers the app?
2. What data is read from Shopify, and at what frequency?
3. What data is written back to Shopify, and under what conditions?
4. Which external systems are touched, and do you already have API credentials and rate limits documented?
5. How many merchant accounts will use this? (Private app = 1. Public = N.)
6. What happens on failure? Who gets notified? How does the state reconcile?
7. What does success look like in measurable terms — conversion lift, time saved, error reduction?

Typical Delivery Timeline

• Weeks 1-2 — Discovery, architecture document, API audit, confirmation of scope and quote.
• Weeks 3-4 — Data model, webhook subscriptions, basic admin UI scaffold.
• Weeks 5-6 — Business logic, external integrations, test coverage.
• Weeks 7-8 — Error handling, reconciliation, observability, admin UI polish.
• Week 9 — Staging with real merchant data, load testing where applicable.
• Week 10 — Production rollout with feature flags, shadow runs, final merchant sign-off.

For the £12-30K bracket, that is typically a 10-12 week engagement. Larger platforms are 4-9 months with phased delivery.

What Drives Cost Down

These genuinely reduce the price on any quote we send:

• Clear written requirements with screenshots or mockups (even rough ones).
• API credentials to all external systems already in a vault we can access.
• A single merchant owner who can make decisions same-day.
• An existing staging store on Shopify Plus we can develop against.
• Willingness to accept Shopify Polaris UI defaults rather than custom design.
• A "ship v1, iterate v2" mindset rather than "launch complete."

What Drives Cost Up

• Requirements that change weekly during development.
• "We need it to work exactly like [competitor we cannot access]."
• External systems with undocumented APIs or no staging environment.
• Multi-stakeholder sign-off chains longer than three people.
• Strict compliance requirements (SOC 2, ISO 27001, medical, financial) added mid-project.

How We Actually Price

Fixed-scope projects for well-defined work, time-and-materials capped at a ceiling for genuinely uncertain work, and monthly retainers once the app is live. The worst outcome for everyone is a fixed-price quote on a fuzzy scope — we have built enough of those to know how they end.