Shopify custom apps
Shopify app development agency for custom apps that run your own rules
Who this is for, and who it is not for
This fits a Shopify or Shopify Plus merchant with at least one of these conditions: staff keep a spreadsheet beside the admin to run a rule Shopify does not hold, a public app needs a workaround for something it was not built for, an integration has outgrown its connector, or nobody in the business can say yes or no to a technical proposal.
It does not fit a store whose need a public app already covers. Buy or configure that app. It also does not fit a team that wants an app built with no owner for it afterwards, because a custom app is software the business now has to run.
A custom app is right when a rule is yours alone
Shopify's help centre defines a custom app as one built exclusively for your store. It can add features to the admin, read store data through the APIs, or extend the store to other platforms through the Storefront API. The decision rule below is our delivery judgement, not Shopify's.
Build when the rule is specific
A pricing, approval or fulfilment rule that exists only in your business, and that a public app can only approximate with a workaround, is the core case for a custom app.
Configure when an app fits
If a public app covers the rule with settings, configure it. Public apps listed on the Shopify App Store go through Shopify's review, and a vendor maintains them, which a custom app does not have.
Use Flow when it stays in Shopify
Shopify Flow is enough while a rule starts and ends in the store. It is outgrown when a second system must agree, a retry is needed when that system is down, or someone needs a record of what failed.
Name an owner before building
A custom app needs someone who decides what it should do, reviews its errors and approves its changes. If nobody will, the answer is a simpler tool, not a build.
Keep the surface small
Each permission an app asks for is a risk and each screen is something to maintain. We ask for the narrowest data access that does the job and document what the app can touch.
A part-time technical lead for merchants without an engineer
This fits a merchant who works with an agency, freelancers and apps but has nobody who can say no to a proposal, compare two quotes or read a pull request. The lead role covers build, buy or configure decisions, an app and vendor review, a second reading of outside developers' work, and the release rules for the store.
It does not replace a full-time engineer. If the work is steady and daily, hire. Hiring a Shopify Plus developer sets out what to look for, and we say plainly when that is the better route.
Headless Shopify is a frontend decision with a running cost
Shopify's developer documentation describes headless as keeping Shopify behind the scenes while you control the frontend, either with Hydrogen, Shopify's official headless framework, or by adding Shopify APIs to an existing stack. Headless earns its cost when a theme cannot deliver a specific storefront experience and your team can own a separate codebase. When a theme is enough, we say so.
Either way, the apps, APIs and integrations behind the storefront need the same ownership and failure handling, and that layer is the work we do.
A Shopify Plus consultant settles ownership before the platform build
Plus adds company accounts and price lists for B2B, Flow, Functions for checkout rules and higher API throughput. The consulting work is deciding which rules live where, which system owns each record and who maintains each piece. We do that, and build and run what follows. See the Shopify Plus agency page for the wider scope.
Public app, iPaaS or custom app: build versus buy
Table: three ways to add a capability to Shopify. Vendor statements come from the Shopify Help Center and the Celigo site (Vendor pages read October 2026). Vendor pricing: not measured. The fit rule is our delivery judgement.
Public app
An app built for many stores. Shopify's help centre says listed and unlisted public apps both go through Shopify's app review, and that some third-party apps bill outside your Shopify invoice.
iPaaS
Celigo says on its site that its iPaaS offers connectors and templates for Shopify. A hosted tool routes, retries and logs without custom code.
Custom app
An app you or a developer builds exclusively for your store, created and managed through Shopify's Dev Dashboard per the help centre. We build the rule, its queue, its retry policy and an exception view.
What we check first before a custom Shopify app is built
Five checks come first, and they can end in a decision not to build.
The installed apps
A list of every app, what it does, what data it can read and whether it is still used. Some of the work is removing overlap.
The rule, written down
The rule in plain language, with the inputs, the expected result and three edge cases, agreed by the person who owns the outcome.
Build, configure or Flow
We test the rule against a public app and against Shopify Flow first, and say so if either one fits.
Data access
The narrowest set of permissions the app needs, written into the specification before any code.
The owner and the failure path
Who approves changes, who reads the errors and what happens when the app is down.
What we run after a custom Shopify app goes live
Go-live starts the work, because an integration is a running system. We run these checks and name who acts on each.
- Monitoring of the app's webhooks and jobs, with a named person for each alert.
- A reconciliation job that finds records the app never received.
- Scheduled upgrades when Shopify retires an API version the app uses.
- A permissions review whenever the app's scope or its owner changes.
- A short written note each month: what failed, what it touched and what we changed.
What our published work shows
Container One sells shipping containers on Shopify Plus, where the delivered price depends on which depot a container leaves from. We matched the old pricing system on 41 of 41 products before any storefront traffic moved, and seeded 40 depots into the new pricing hub. The migration is still in progress. Read the Container One case study.
SENE Studio is a made-to-measure clothing brand whose Shopify operations platform sends each order to an outside garment factory. In eight weeks, 37 changes reached the branch behind real orders and none merged without a named person accepting it. One 13-row admin page dropped from 113 database queries to 17. Hours saved were not measured, because no baseline was taken. Read the SENE Studio case study.
Other systems and the wider integration scope
The integrations hub sets out how we choose between a native app, an iPaaS and a custom build for any system. Guides to the others we connect most often:
Common questions
What does a Shopify app development agency do?
It builds, maintains and documents software that extends Shopify: custom apps, integrations, checkout rules and internal tools. A good one also says when a public app or Shopify Flow is enough, and names who owns the app after launch.
When should I build a custom Shopify app instead of buying one?
Build when the rule is specific to your business, no public app expresses it without a workaround, and someone will own the app afterwards. Buy or configure when an existing app covers the rule with settings.
What is a part-time technical lead for Shopify?
A named person who makes the technical decisions a merchant without an engineer cannot: build or buy, which vendor, whether a contractor's work is safe to ship. It suits a store with apps and agencies but no in-house developer. It is not a full-time hire.
Is headless Shopify worth it?
Only when a theme cannot deliver a specific storefront experience and your team can own and run a separate frontend codebase. Otherwise a theme is cheaper to keep running. Decide on the experience you need, not on the architecture.
What does a Shopify Plus consultant do that an agency does not?
A consultant decides which rules, records and responsibilities live where before anything is built. An agency builds. We do both, so the decision and the build share one owner, and we say so when the answer is not to build.
Migration & Replatforming
Workarounds around apps that almost fit cost more than a custom build
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