An ecommerce website design agency designs and builds the storefront a shopper actually uses. That includes category pages, product pages, cart and checkout, plus the platform setup behind them.
The decision that separates a good engagement from a bad one is simple. It is how much conversion thinking goes into the brief before design starts.
This post covers the design and build stage, before the store exists or during a rebuild. Three project types need three different briefs: a new build, a redesign, and a replatform. Know which one you are doing before you write a word of the brief.
Step 1: Decide whether this is a new build, a redesign or a replatform
Every ecommerce project falls into one of three categories. The category changes what you should ask for.
A new build starts with no catalogue and no traffic history. There is nothing to migrate and no rankings to protect. The brief is mostly about content readiness: how many templates you need, and whether product content exists yet.
A redesign keeps the same platform and swaps the front end. Most URLs survive untouched. The real risk is invisible: losing behaviour that worked, because nobody wrote down why a page did what it did.
A replatform moves an existing store onto a new platform. Everything changes: URLs, product data structure, review content, even what the checkout is allowed to do. It is the highest risk project type, and the least written about.
| Project type | What you are actually buying | Biggest risk | |---|---|---| | New build | Templates and a working storefront | Content is not ready when design needs it | | Redesign | A new front end on the same platform | Losing behaviour nobody documented | | Replatform | A store rebuilt on new infrastructure | Broken redirects cost you rankings |
Name the project type on the first line of your brief. It changes what a good agency should ask you next.
Step 2: Put the conversion decisions in the design brief, before wireframes
Agencies design to the brief they are given. A conversion decision left out of the brief becomes a change request after launch. That is when it is most expensive to fix.
This is the same argument behind building conversion into design from day one. The brief is just where it starts.
Product page requirements to write into the brief
- Full delivered price rules: does shipping and tax show before the cart, and where.
- Content fields required per product type, named directly: size guide, materials, dimensions, compatibility.
- Photo spec: how many angles, a scale reference, who supplies the photos and by when.
- Variant behaviour specified, not assumed. Variants with no stock get disabled rather than silently missing. The variant shows in the URL so it can be shared. The gallery follows whichever variant is selected.
- Delivery shown as a date, not a shipping class name, and which system supplies that date.
- Review display rules: where reviews render, whether negative reviews show, and the minimum count before the block appears.
- Content ownership and a deadline. In the builds I have worked on, missing product copy is the most common reason a schedule slips.
Take a homewares catalogue, an anonymized composite rather than any one client. Specify that gallery images swap with the selected colour, not just the swatch. Skip that detail and someone adds the wrong colour to cart, because the photo never changed.
Cart and checkout rules to agree before design starts
- A maximum checkout field count, agreed in writing before wireframes exist. Treat it as a ceiling, not a target.
- Guest checkout required. Offer account creation after purchase, on the confirmation page.
- Cart editing happens in place, with no full page reload.
- Discount code field placement decided on purpose, not dropped in wherever the theme puts it.
- Payment methods and wallets your market actually uses, named in the brief.
- A rule for failed validation: it never clears what the customer already typed. This is one case of a general form design rule, preserve everything on a failed submit.
- Address autocomplete in or out, and which vendor if it is in.
Trust signal placement, decided on the wireframe
- Returns and shipping policy summarised on the product page itself, not buried in the footer.
- A contact route a real person answers, reachable from every step of the funnel.
- Payment and security marks placed at the payment step, where the doubt actually lives.
- Stock and dispatch honesty rules written down, so nobody invents urgency copy later.
Adding trust signals after launch means reopening a template that is already approved. Deciding placement now is cheaper than that conversation later.
Once the store is live and has real traffic, measuring what shoppers actually do is a different job. That is what the ecommerce CRO audit covers.
Step 3: Plan redirects and data migration before the redesign starts
In my experience, a replatformed store loses rankings through broken redirects more often than through anything a designer got wrong. It is the step almost nobody plans early enough for.
Crawl and export every live URL before design begins, not the week of launch.
Map old to new one to one: product URLs, variant URLs, category and filter URLs, blog posts, and images.
Use permanent redirects. Avoid chains where one old URL hops through two or three others before it lands.
Structured data and canonical tags get rebuilt on the new platform. Put them in scope rather than assuming they carry over.
Review content is page content too. It often lives inside a platform app and does not travel with a migration. In an anonymized composite of replatform work like this, years of reviews vanished at cutover because nobody exported them first.
Ask for the URL export as a deliverable, not an afterthought. If it exists in writing, someone is accountable for it.
Re-crawl after launch against your original URL export, and check what broke.
A short dip after a replatform is normal. A sustained one usually means the redirect map was wrong.
Put ownership of this in the contract. Agencies and store owners both routinely assume the other side has it covered, and that is exactly how it gets missed.
Step 4: Choose the platform while you are still writing the brief
The platform decides what your checkout is allowed to look like. Choose it after the designs exist, and you will be redrawing them.
A few things should drive the decision:
- Catalogue size and variant complexity
- Whether you need to control the checkout itself
- Subscriptions or B2B pricing
- Integrations you already run
Platform capability changes often enough that a comparison table goes stale within months. What each platform lets you change at checkout is covered against a live store, where it belongs.
Step 5: What to ask an ecommerce website design agency before you sign
- Who actually does the work, and are they the people in this meeting? A good answer names individuals, not just the agency.
- Who owns the code, design files, domain, and analytics accounts after launch? The right answer is you, in writing.
- What happens to the site if the relationship ends? You should walk away with a working store either way.
- How will checkout work on the platform you have chosen? A good agency explains this without hedging.
- Who owns the redirect map on a replatform? Someone specific, not "the developer will handle it."
- What is explicitly out of scope, and what does a change request cost? Vague scope is where budgets quietly grow.
Step 6: Work out what actually drives the cost
Published price ranges for this work vary so widely they are not worth repeating here. Cost comes down to a few drivers:
- Catalogue size and variant count
- Number of unique templates
- Integrations you need
- How ready your content is
- Migration scope
- Support after launch
What a fixed price quote does when scope moves is worth reading before you sign anything.
Template, solo design engineer or agency
A hosted template store is genuinely the right call for a small catalogue and a tight budget. Say so plainly instead of talking it down.
An agency buys you a full team and more process. That suits a large catalogue with several complex integrations.
There is a middle path I work in myself. One senior person designs and builds the store end to end. The full version of that trade off sits in the four ways to get a small business site built, and the same call shows up for a general contractor's website or a medical practice's website.
If your project fits the design and build stage this post covers, the website design service is where to start.