Creating an e-commerce site is not just about "putting products online." You are building a system that must sell, reassure, collect payments, deliver, manage returns, provide reliable data, and integrate with your organization. When a project starts without a framework, the same problems almost always arise: impossible-to-compare quotes, delays, "forgotten" features, fragile SEO, average performance, and a store that is difficult to manage on a daily basis.
The specifications document is therefore not an administrative document. It is the best guarantee for the success of your e-commerce site creation, whether you work alone, with a freelancer, or with an agency. In this guide, you will build clear, concrete, and actionable specifications, with a template and a checklist at the end.
Even before choosing a platform or design, it is essential to understand what differentiates a simple merchant site from a truly high-performing store. Catalog architecture, mobile experience, conversion strategy, natural referencing, and brand perception play a central role in the success of an e-commerce project. We have detailed these fundamentals in our complete guide dedicated to online sales sites in France, to help brands build a store truly designed to sell.
Why specifications are the true first step
On an e-commerce site, what you see is rarely what costs the most to fix. The design and pages are visible, but the essence lies hidden in what is managed from the back office: variant management, shipping cost calculation, taxes, multi-channel inventory, transactional emails, SEO redirects, tracking, and checkout. If these topics are not addressed beforehand, they can become real problems later on.
A specifications document brings you three immediate benefits. First, it transforms your intentions into decisions. Second, it makes your priorities explicit (what is essential for launch, what can wait). Finally, it allows you to obtain comparable quotes, because everyone responds on the same basis.
In other words: the creation of an e-commerce site is not decided when you choose a platform or a service provider. It is decided when you precisely define what the site must achieve, and how.
Business objectives: what the site must "sell" (and measure)
An e-commerce site sells products, but it also sells trust. Your specifications therefore begin with your business objectives, not with a list of features. A site built to develop acquisition does not look like a site built to maximize repurchase. A site that aims for margin is not managed like a site that aims for volume.
Describe your main objective in simple words: increase turnover, reduce dependence on marketplaces, improve profitability through direct sales, develop a customer base, launch a range, open a new country. This sentence will serve as your compass for arbitrating the rest.
Then, specify how you will measure success. The right level of monitoring is not "measure everything," it is "measure what guides your decisions." An average basket, a conversion rate, a payment abandonment rate, a return rate, a share of recurring customers: these indicators are already very helpful. They prevent you from judging the site on impressions.
Finally, be realistic about your internal constraints. Who manages the catalog? Who responds to requests? Who prepares orders? In e-commerce site creation, the tool is never the real problem. The real problem is the organization that must feed and operate it.
Catalog: products, variants, bundles, filters, search
The catalog is often the first source of friction because it is rarely conceived as a structure. Yet, it is what determines your navigation, your filters, your SEO pages, your merchandising, and even your customer service.
In the specifications, describe your catalog as a system. How many actual references? How many variants per product? Do you have customizable products? Options that modify the price? Stock or preparation constraints? These elements dictate how product sheets are built and how inventories are managed.
Also specify your content standard per sheet. A high-performing e-commerce sheet is not a simple description. It must explain the benefits, address objections, clarify usage, and prove quality. If your positioning is premium, this generally implies more useful images, more proof, more clarity, and less noise.
Then, formalize your package and recommendation strategy. Do you want to offer bundles, lots, complementary products, or offers that increase the average basket? This is not a detail. It is often one of the best ways to optimize the profitability of an e-commerce site, provided it is integrated from the design stage.
Finally, approach search and filters using the customer's vocabulary, not your internal vocabulary. A "material" or "format" filter is useful, but a "use" or "need" filter is often even more so. An efficient search saves the visitor time and increases the store's turnover.
Customer journey: essential pages + mobile-first UX
The majority of e-commerce sessions take place on mobile, and the majority of friction comes from a journey that is "adapted" rather than designed for mobile. Mobile-first does not mean "smaller version." It means: clear reading, simple thumb actions, a neat information hierarchy, and reassurance at the right time.
In your specifications, describe the journey before describing the pages. How does the customer discover your products? How do they compare? What reassures them? When do they see the full price, delivery times, and shipping costs? When do they register, and why? This narration highlights the stages of decision-making.
Some pages are obviously essential (homepage, categories, product sheets, cart, payment, trust pages), but efficiency lies in the sequence. A product sheet, for example, must make you want, then clarify, then prove, then secure. On mobile, this often involves a clean structure, with readable sections and a well-placed call to action, without being aggressive.
If you want to go further on commercial effectiveness once the site is online, keep this guide handy for improving your Shopify conversion rate. It will help you prioritize the optimizations that have the most impact.
Payment, delivery, returns, taxes: rules and edge cases
This is the most "operational" part of the specifications, and paradoxically the easiest to write. Why? Because this is where the edge cases live. And that's exactly what creates delays and cost overruns if you discover them too late.
Regarding payment, describe what is essential for your market and your target. Expectations are not the same depending on the country. Also clarify the rules: payments in installments, deferred payments, B2B with validation, or quote management. The goal is for the purchasing journey to match the reality of your customers.
Regarding delivery, go beyond "we will deliver everywhere." Where do you start from? Which zones? Which carriers? What are realistic delivery times? How are costs calculated? What happens if a cart contains a heavy product, a fragile product, or a pre-order product? A high-performing e-commerce site is often one where delivery is understood, not guessed.
Regarding returns, be clear. Deadline, conditions, who pays, refund or credit, exchange or not. A legible return policy reassures, and reassurance sells. Conversely, a vague policy costs in customer support and conversion.
Finally, define the fiscal and geographical scope. France only, Europe, international. Even without going into legal details, this decision conditions delivery, mentions, VAT, and sometimes the payment experience.
SEO: architecture, collections/categories, content, redirects
An e-commerce site can be very beautiful but invisible. SEO is not a layer that is added at the end: it is a way of organizing your online store to match demand and allow search engines to understand your offer without ambiguity.
In the specifications, start with the architecture. Define your main categories and the sub-category logic. The key is clarity: each important page must respond to a unique intent, with a unique angle, to prevent multiple pages from competing for the same queries.
Next, define your content strategy. On an e-commerce site, useful content is not just "a blog." It also includes category pages that guide, product sheets that explain, guides that reassure, and trust pages that clarify. Your SEO primarily depends on your ability to publish useful and consistent content with customer searches.
If you are migrating or redesigning an existing site, the redirection plan is non-negotiable. It protects your traffic, your positions, and your history. To frame this topic in detail, you can refer to Shopify redesign: securing SEO and conversion, which details the migration logic and points of vigilance.
Tracking & data: GA4, pixels, consent, events to plan
Without reliable data, you optimize by instinct. And in e-commerce, instinct is often misleading, because problems hide in the details: a shipping cost that arrives too late, a missing payment method, a product sheet that doesn't explain enough, a mobile that's too slow.
Your specifications must define what you want to measure to guide: product visibility, additions to cart, payment starts, purchases, but also performance by channel and by product. The principle is simple: measure what helps you decide, not what gives you an "impressive" dashboard.
Plan for a clean installation of Google Analytics 4 and, if you advertise, appropriate pixels. Also think about consent: it must be compliant, but it must remain understandable and not break the experience. Imperfect but consistent measurement is better than "complex" measurement that no one understands.
Integrations & operations: ERP/PIM/WMS, marketplaces, email, after-sales service
An e-commerce site is not an isolated project. It fits into your daily life: inventory management, order preparation, invoicing, customer support, email marketing, sometimes marketplaces and points of sale. The earlier you clarify these interactions, the more stable and simple your site will be to manage.
Start by identifying the single source of truth for stock and catalog. If your stock lives elsewhere than in the online store, you need to define how and how often it synchronizes. Late-displayed out-of-stocks are a direct source of frustration and support tickets.
Then, describe your email and customer service needs. Transactional emails must be clear, reassuring, and consistent with your brand image. Customer support must have a simple path: contact, order tracking, returns. The goal is not to pile up tools, but to build a fluid journey, both for the customer and the team.
If you also sell on marketplaces, specify your expectations: stock synchronization, order management, price consistency, return management. Even if you start simple, writing down the target prevents you from rebuilding later.
Performance & quality: speed, accessibility, QA, testing
Performance is one of the most underestimated levers in e-commerce site creation. A slow site decreases conversion, increases acquisition cost, and degrades the mobile experience. Quality is not just "it works." It is proven by structured testing.
In your specifications, define a clear objective: a fast, stable, pleasant site on mobile, even in average network conditions. This influences very concrete choices: image weight, animation sobriety, application selection, and technical discipline.
Then, plan for testing before launch. Useful testing covers key journeys and edge cases: adding to cart, promo codes, shipping costs, taxes, emails, payment, returns, mobile display. This testing time is often what differentiates a serene launch from a painful one.
Also consider accessibility and readability. Contrasts, text sizes, clear buttons, consistent navigation. This is not a luxury, it's a way to reduce friction for everyone.
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Catalog, customer journey, SEO, tracking, logistics, integrations, performance, and testing: I can help you frame the scope, identify edge cases, and transform your needs into truly actionable specifications.
Discuss your specificationsPlanning & budget: how to estimate (MVP vs V2)
A realistic budget is built on a clear scope. Without specifications, you get either a vague quote or an overly optimistic one. With specifications, you can estimate the project by versions.
The MVP is not a "discounted" site. It is a site that perfectly covers the essential scenarios for proper selling: clear catalog, fluid mobile journey, reliable payment, transparent delivery, healthy SEO base, and exploitable tracking. V2 comes next, fueled by data: more advanced bundles, automations, content enrichment, conversion optimizations, additional integrations.
In the specifications, write down what is essential for launch and what can wait. This simple separation protects your planning, your budget, and your quality.
How to use this document to request 2-3 comparable quotes
Good specifications should allow several service providers to respond with the same level of understanding. When you request quotes, it's not just the price that needs to be comparable: it's the scope, the assumptions, the deliverables, and the methodology.
Send the document, then explicitly ask for a structured response: what is included, what is optional, what depends on prerequisites, and how testing and launch are managed. This is also when you can decide whether you want to choose an agency to create an online store or prefer another organization. The important thing is to obtain truly comparable proposals, rather than three different visions of the same project.
If you're going with Shopify
If your e-commerce site creation is oriented towards Shopify, the challenge is often to start with a clean, fast, and easy-to-maintain base, while maintaining flexibility for evolution. For a step-by-step method, you can follow create a Shopify store yourself (tutorial), which details a structured approach from framing to launch.
E-commerce specifications template
Finally, here is a simple framework you can copy and paste. The idea is not to produce a huge document, but a clear one that aligns your objectives, scope, and constraints.
1) Context and objectives. Explain your business, your target, your promise, and what your e-commerce site creation must primarily achieve.
2) Success indicators. Define the metrics that will guide your decisions after launch, without trying to measure everything.
3) Catalog. Describe the product structure, variants, inventory management, and the expected content level on the product sheets.
4) Customer journey. Describe the ideal visitor journey, especially on mobile, and specify the reassurance points.
5) Payment, delivery, returns, taxes. Write down the rules and edge cases that your store must manage unambiguously.
6) SEO. Define the tree structure, priority pages, content strategy, and, if necessary, the redirection plan.
7) Tracking. Define what you want to track and how you will use this data to guide your decisions.
8) Integrations. List the tools to be connected and clarify the single source of truth for stock and catalog.
9) Quality and performance. Set a speed objective and a testing plan before launch.
10) Planning and versions. Clearly separate MVP and V2 to secure budget, deadlines, and quality.
Conclusion. A successful e-commerce site creation is a site that sells, is manageable, and can evolve without being rebuilt. The specifications are the framework that enables this success. If you do it right, you save time, avoid surprises, and maximize your chances of having a high-performing store from the very first weeks.
Do you want to turn your specifications into a Shopify store?
I am Olivier Romero, founder of Agence Shop. We support brands from project framing to the launch of their Shopify store, combining e-commerce strategy, UX, design, development, SEO, and CRO.
Our goal is to start with a clear scope, avoid unpleasant surprises during production, and build a high-performing store that is easy to manage and capable of evolving over time.
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