Custom Shopify app development in Canada: cost and options

Most people who search "custom shopify app development canada" want a number first. As Treevoxa's planning ranges stood in October 2026, a small admin or checkout tweak is roughly CAD 2,000 to 6,000. A single integration, such as stock sync, is about CAD 6,000 to 18,000. A full ERP and fulfilment sync with proper exception handling is usually CAD 18,000 to 50,000. A public App Store app starts around CAD 40,000. These are estimates, not quotes, and scope moves them more than anything else. If you want to see what we build, start with our custom Shopify app development page.

A custom Shopify app beats an App Store app when the store has to follow your rules, not the app's. That usually means ERP sync, multi-location stock, odd fulfilment logic or B2B pricing. If an App Store app does the job without workarounds, buy that instead.

This guide is for Canadian merchants, and for businesses selling into Canada. The tax and privacy sections are practical guidance, not legal or tax advice.

1Do I need a custom Shopify app?

Start with the App Store. If an existing app does 80% or more of the job with no workarounds, install it. A monthly app fee is almost always cheaper than a build.

You probably need custom if several of these are true:

• Orders, stock or customers have to sync with an ERP or inventory system, and no listed connector fits yours.
• You hold stock in several locations (warehouse, retail store, 3PL) and need rules for which one fulfils which order.
• Fulfilment has exceptions: partial shipments, backorders, split orders, special carrier rules.
• B2B customers need their own price lists, credit terms or approval steps.
• Checkout needs logic that Shopify's settings can't express.
• You pay for three or four apps that overlap, each with its own quirks and fees.
• A manual process costs you hours every week and keeps causing errors.

If none of these apply, a custom app is probably the wrong tool. For the wider build-or-buy question, read custom software vs SaaS, or ask our software consulting team for an independent view before you commit to anything.

2Custom, public or private app: what is the difference?

A custom app is built for one merchant (or a closely related group of stores). A public app is built for many merchants, and Shopify reviews it before listing it on the App Store. Private apps were the older way of building for a single store with fixed credentials.

Shopify has changed how custom apps are created and is moving away from legacy private apps and apps created inside the store admin, towards the Dev Dashboard. Third-party explainers disagree on dates. One gives 1 January 2026 for the end of admin-created custom apps, and we have not relied on it. Read the current Shopify Help Center page on making apps before you plan around any explainer, including this one. Your developer should confirm which creation route applies to your store today.

You need a Shopify Partner account to build, and it is free. Developers use it to create development stores, where the app is built and tested without touching your live shop.

Do you need Shopify Plus? Not for most custom apps. Some checkout customisations and Shopify Functions options depend on your plan, so confirm what your plan allows before designing around it. Plus is priced on a contract, so check shopify.com for the current fee before it enters your budget.

3How much does custom Shopify app development cost in Canada?

The bands below are Treevoxa's own planning ranges in CAD as at October 2026, excluding GST/HST. They are ranges, never fixed prices, and a proper quote needs a discovery step. For a US dollar view, see our guide to Shopify app development cost.

What moves the price most

• How many systems the app touches. A standalone checkout rule is cheap. An app that talks to Shopify, an ERP, a warehouse and a carrier has four sets of data rules to agree.
• How messy your data is. Duplicate SKUs, free-text product codes and stock held in spreadsheets add weeks, whatever the hourly rate.
• Who builds it. A Canadian agency, an offshore team and a freelancer price the same scope very differently. The comparison section below covers this.
• What happens after launch. Hosting, support and Shopify's API upgrades are ongoing costs, not one-offs.

A worked example

This is an illustration with assumed rates, not a quote. Take an ERP sync for a merchant with two warehouses:

Assume a blended offshore rate of CAD 70 an hour. That gives about CAD 19,200. Assume a Canadian agency rate of CAD 140 an hour, and the same 274 hours come to about CAD 38,400. Both sit inside the ERP band above. The hours barely change between the two. The rate and the overheads do.

Why published rates disagree

Published hourly rates are hard to compare. One cost guide quotes USD or CAD 120 to 200 an hour for the US and Canada without saying which currency. Another puts Canadian developers at CAD 50 to 180 an hour depending on seniority. That is a threefold spread inside one guide.

Currency is often unstated, junior and senior rates get blended, and agency overheads vary widely. Compare quotes by total hours, who does the work and what is included. When you hire a Shopify developer in Canada, ask for hours and rates separately. Our software development rates page shows how we price, and the software development cost calculator gives a rough figure for your scope.

Ongoing costs after launch

A custom Shopify app cost does not stop at go-live. Budget for these every year:

• Hosting and monitoring: usually modest next to the build, but ask for a monthly figure, since heavy sync traffic costs more.
• Support: a monthly retainer or an hours bank for fixes and small changes.
• API version upgrades: Shopify releases versioned APIs on a regular schedule and retires old ones. Check the developer documentation for the current cadence, then plan for periodic upgrades.
• Third-party fees: your ERP's API access, carrier accounts, error-monitoring tools.

4How long does a Shopify app project take?

The timeline column above is a fair guide. Small tweaks take 2 to 4 weeks, integrations 4 to 8, ERP sync 8 to 14, and a public app 3 to 6 months plus Shopify's review time.

Most projects follow the same phases:

1. Scoping: agree the data flows, the system of record for each field, and what counts as done.
2. Build on a development store: nothing touches your live shop yet.
3. Testing: with realistic data, including the awkward orders.
4. Launch: often a staged cut-over, one location or product range first.
5. Hypercare: a few weeks of close monitoring while real orders flow.

What slows projects down is rarely the code. It is unclear ERP data, slow approvals on your side, and waiting for API access from the ERP vendor or warehouse.

5How do I connect Shopify to my ERP, stock and fulfilment?

This is the most common real reason to build a custom app, and most agency pages barely cover it. Shopify ERP integration is also where we spend most of our time. Our work on ERP software development and API development feeds directly into it. If you are still choosing a platform, see custom ERP vs Odoo vs ERPNext.

The job is to decide which system owns which data, then move it reliably.

The details that cause trouble

Webhooks. Shopify tells your app about events with webhooks, but delivery is not guaranteed to happen exactly once. Messages can arrive twice, late or out of order. Your app must verify each webhook's signature, respond quickly, then process the job from a queue. It should also use the webhook ID to ignore duplicates. That property is called idempotency, and without it you get duplicate orders in the ERP.

Rate limits. Shopify's Admin API limits how much work you can request, using a cost-based allowance that refills over time, with different limits by plan. Check the current figures in the developer documentation. A catalogue update of 20,000 SKUs sent in one burst will be throttled. Good apps queue requests, back off when throttled, and use bulk operations for large jobs.

Multi-location inventory. Shopify tracks stock per inventory item per location. Your ERP may hold one total, or its own warehouse codes. You need an explicit map from ERP warehouses to Shopify locations, and a rule for what "available" means once reserved and committed stock are counted.

SKU mapping. Every variant needs one stable identifier shared by both systems. Fix duplicates and blanks before the build, not during it.

Returns and partial shipments. An order that ships in two parcels, or comes back in part, must update stock and accounting correctly. Test these cases deliberately.

Carriers. Canada Post, Purolator, UPS and others each have their own rate and label logic. Whether carrier-calculated rates are available depends on your Shopify plan, so check before designing around them.

What does a sound sync design look like?

These rules cover most designs:

• One system of record per field. If both systems can edit stock, you will eventually overwrite one with the other.
• Event-driven, plus a nightly reconcile. Events keep things fast. The reconcile catches what events missed.
• A dead-letter queue and alerts. Failed jobs go somewhere visible, and a person is told.
• Safe re-runs. Running a job twice must produce the same result as running it once.
• Test on a development store with realistic data. Copy a month of real orders, including the odd ones.

The trade-off is cost. Reconciliation reports, queues and alerting add build effort and some running cost. They are also what separates a sync you trust from one that has you firefighting for the first month.

6How do GST, HST, PST and QST affect the app?

Canadian sales tax depends on the province and the customer's destination. HST applies in Ontario and the Atlantic provinces. GST plus PST applies in British Columbia, Saskatchewan and Manitoba. GST plus QST applies in Quebec. Alberta and the territories charge GST only. Rates and rules change, so treat this as orientation, not a reference.

Do not make your app reinvent this. Let Shopify Tax in Canada or your store's tax settings calculate it. Your app's job is to carry the result faithfully:

• Pass the tax lines Shopify calculated into the ERP, split by component (GST, PST, HST, QST), rather than recomputing them.
• Map Shopify tax lines to your ERP's tax codes in a table that someone in finance owns.
• Watch rounding. Two systems can differ by a cent per line, and that adds up in reconciliation.
• Decide how tax-exempt customers and B2B accounts are flagged, and who maintains the list.

Registration thresholds and filing rules sit with the Canada Revenue Agency and, for QST, Revenu Québec. Confirm them with your accountant, not a developer. This is not tax advice.

7Does Quebec Law 25 or PIPEDA apply to my app?

Probably yes, in some form. The federal PIPEDA applies to private-sector commercial activity across Canada. As we write in October 2026, a proposed bill to replace it with stronger penalties has stalled and is not current law, so plan around PIPEDA as it stands and check the Office of the Privacy Commissioner of Canada for any change. For Shopify-specific summaries, see these guides on PIPEDA and Quebec Law 25.

Quebec Law 25 was phased in from 2022, with most obligations in force by September 2023. It can reach businesses outside Quebec that collect Quebec residents' personal information. Confirm your position with the Commission d'accès à l'information du Québec.

For an app, the practical points are:

• Consent: record what customers agreed to, and when.
• Data minimisation: store only the fields the app needs.
• Where data is stored: Law 25 sets conditions, including an assessment, for personal information leaving Quebec. Know where your app and its vendors host data.
• Breach logging: keep a record of incidents and who was told.
• Vendor access: know exactly who on the developer's side can see customer data, and remove access when the project ends.

French is a separate point. Quebec's language rules, updated by Bill 96, push towards French being available for customer-facing text such as emails, labels and checkout messages. Build the app with translation in mind from day one, because retrofitting it costs more. This is not legal advice, so take legal advice on what applies to you.

8Local Canadian agency, offshore team or App Store app?

A Canadian agency costs more because of local salaries and overheads. What the difference buys you is the same working hours, on-site workshops, a local contract and local legal recourse. For some merchants that is worth paying for.

An offshore software development team can deliver sound work at a lower rate, if scope, communication and testing are disciplined. Quality varies by team, so ask to see shipped integrations rather than assuming. A hybrid often works well: a local product owner or consultant sets the scope and tests, while an offshore team builds. If you would rather extend your own team, the dedicated development team model is another route.

9Who owns the code, and what should the handover include?

You should own it, and the contract should say so in plain words. Check these before signing:

• Code ownership transfers to you on payment, with no licence-back conditions.
• Repository access: the code lives in a repository you own, or you get a full copy at every milestone.
• Hosting in your name: the cloud account, domain and database belong to you, not the agency. An app hosted on the developer's account gives them leverage you do not want to hand over.
• Secrets and keys: API keys, tokens and credentials handed over, then rotated at the end of the project.
• Documentation and a runbook: how it works, how to deploy it, and what to do when a sync fails.
• A warranty period: a defined window of free bug fixes after launch. Agree the length in writing.

10How do I choose and brief a developer?

Do not treat a "top 10 agencies in Canada" list as proof. Many are written by agencies that place themselves near the top. Ask each shortlisted developer these questions instead:

• Show me a similar integration you have shipped, and let me speak to that client.
• Can you run a fixed-scope discovery before quoting the build?
• Who will actually write the code, and who will I talk to?
• How do you test, and will you use a development store with my real data?
• What are the support terms after launch, and what do they cost?

A one-page brief is enough to get useful quotes. Include:

• Your current systems (Shopify plan, ERP, warehouse, carriers).
• The three to five processes the app must automate.
• Order and SKU volumes, and how many locations hold stock.
• Provinces you sell into, and whether French is needed.
• Your budget range and the date you need it live.

With that brief, a developer offering custom Shopify app development can give you a realistic range instead of a guess.

11What should I do before asking for quotes?

Before you commission custom Shopify app development in Canada, write down which system owns stock, orders and prices today, and where the two disagree. Export a sample of SKUs and look for duplicates and blanks. Check whether an App Store app already covers 80% of the job. If it doesn't, you now have the material for the one-page brief above, and any quote you receive will be easier to compare.