When a custom ecommerce build is the right call
Most custom ecommerce builds we are asked to review should not have been custom. They were commissioned because a platform felt limiting during a demo, not because a rule genuinely did not fit.
There are, however, four situations where custom is plainly correct, and in those cases trying to force a platform is the more expensive mistake.
The four justified cases#
- Pricing or entitlement logic that depends on who is logged in, in ways the platform cannot express.
- Order volume where per-order fees exceed the cost of running and maintaining your own system.
- The store must live inside systems you already own — an ERP, a booking engine, a member database.
- Commerce is part of the product you sell, so the experience is a competitive asset, not a cost centre.
What custom actually costs#
| Item | Typically underestimated by |
|---|---|
| Checkout edge cases (failed payment, partial stock, refunds) | 2× |
| Tax and shipping rules per market | 2–3× |
| Admin tooling your team needs daily | 3× |
| Ongoing maintenance and security | Entirely — often not budgeted |
| The second market or currency | Assumed to be free; is not |
The hybrid that usually wins#
Keep a proven commerce engine for catalogue, cart, payment and orders. Build custom only the layer that is genuinely yours — configurator, quoting, entitlements, a pricing engine. You get the strange rules and skip rebuilding refunds.
Anything involving money movement, PCI scope or tax is the least rewarding thing to write from scratch.
A test before you commit#
Write down the three rules that a platform supposedly cannot handle. Then try to implement them on the platform with an afternoon of effort. Two out of three usually turn out to be possible, and the remaining one tells you exactly how much custom you actually need.
Frequently asked questions
Is custom better for performance?
Not inherently. Performance comes from caching and disciplined pages, both available on platforms.
Who maintains a custom store?
Someone must, permanently. Budget 15–25% of build cost per year and name the owner before you start.
What is the safest custom scope?
The layer unique to your business, sitting on a proven engine for payment, orders and refunds.
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