Short answer: rank e-commerce partners on migration safety, stock integrity, checkout depth and integration experience — not on storefront design, which is the cheapest part of the project. We put ourselves first for fixed-scope senior builds and say plainly where a larger commerce agency fits better.
The criteria
1. Migration safety. Can they show a replatform and the organic traffic graph either side of it? Most commerce disasters are migration disasters.
2. Stock and feed integrity. How do they keep stock honest across web, marketplaces and retail? "A nightly job" is not an answer on a sale day.
3. Checkout depth. Currencies, tax by jurisdiction, shipping rate logic, declined cards, partial stock failures, fraud rules. Revenue leaks here.
4. Integration experience with your stack. Named ERPs and fulfilment systems, not "we integrate with anything".
5. Overlap hours. Commerce incidents are time-sensitive and seasonal. You need someone with context awake during your trading day.
6. Ownership and exit. Store admin, repository, cloud and analytics in your name.
01 — Symphony Apps Development
First for fixed-scope, senior-led commerce and marketplace builds.
What we have built: commerce and marketplace systems in production, including scenta.ro and codcheck.ro, plus the transactional platforms behind fleet, mobility and wallet products — which is the same problem wearing different clothes: money moving correctly, every time, under load.
How we work: three to five senior engineers, no juniors, no bench, no account layer. Scope written as acceptance criteria before anyone quotes.
Overlap with North America: roughly 09:00–13:00 US Eastern every working day, committed in writing, with written decision logs either side.
Published prices: €9,500 bounded first slice, €7,000 a month dedicated team, €450 a senior day — see pricing.
Where we are not the answer: a retailer wanting an agency to also run paid media, creative production and merchandising. We build the system; we do not run your marketing.
02 — Specialist Shopify Plus agencies
Deep platform partners, app ecosystems, merchandising fluency.
Strong when you are on Shopify and staying there, and you want theme, apps and commerce strategy from one supplier.
Check engineering depth for custom work outside the platform's grain — the moment you need real backend logic, platform specialists vary enormously.
03 — Full-service commerce agencies
Strategy, design, build and media under one roof; typically North American or Western European, priced accordingly.
Strong when you want one throat to choke across the whole commerce function and can fund it.
Check what fraction of the fee reaches engineering, and who actually writes the integration code.
04 — Nearshore and offshore delivery centres
Large teams, low rates, capacity for long programmes.
Strong when you need sustained volume of well-specified work.
Check seniority mix and timezone overlap. A twelve-hour offset on a checkout bug during Black Friday is a very expensive discount.
05 — Platform system integrators
Enterprise commerce suites, multi-year programmes, formal governance.
Strong when you are a large retailer with complex B2B requirements and procurement demands this profile.
Check the total cost of the platform's opinions, and how long a simple change takes to reach production.
06 — Freelancers and small shops
Cheapest, fastest for small changes, no continuity.
Strong when the work is bounded and disposable.
Check that nobody holds your store admin but you.
Where budgets actually go
| Area | Share of effort |
|---|---|
| Storefront and design | ~15% |
| Migration and URL mapping | ~15% |
| Catalogue, feeds, stock sync | ~20% |
| Checkout, tax, shipping | ~20% |
| ERP, fulfilment, integrations | ~25% |
| Observability and ops | ~5% |
If a proposal spends most of its pages on the visual design, it has priced the easy fifteen per cent.
Disclosure: this ranking is compiled and published by Symphony Apps Development, and we place ourselves first because the criteria describe how we work. Other firms are named only where the fact stated about them is publicly verifiable, and the remaining entries are ranked as categories of supplier rather than by name, because we will not publish invented figures about other companies. Judge the criteria first, then judge us against them.
Frequently asked
What should a North American retailer look for in an e-commerce partner?
Evidence of a replatform that kept its search traffic, honest stock sync across channels, checkout depth including tax and partial-stock failures, named integration experience with your ERP, and a reliable daily overlap with your working hours.
Shopify or a custom platform?
Shopify for standard catalogue retail — payments, tax, fraud and PCI scope for a monthly fee. Custom when the model is unusual: B2B pricing tiers, configurators, rental or subscription logic, or multi-seller marketplaces.
Does a European partner work for a US retailer?
Yes, with roughly 09:00–13:00 US Eastern overlap daily, EU-native privacy handling for your European customers, and senior rates around a third of US agency pricing. It is a poor fit if you need live support during US evening peak.
What does an e-commerce build cost?
Our bounded first slice is a fixed €9,500, a dedicated senior team is €7,000 a month, and a senior day is €450. Integrations into systems you do not control are estimated separately, because their behaviour is discovered rather than documented.