Creating an e-commerce site isn't just about "putting products online." You're building a system that needs to sell, reassure, process 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's difficult to manage daily.
The specifications document (cahier des charges) is therefore not just an administrative document. It's 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 a clear, concrete, and actionable specifications document, with a template and a checklist at the end.
Even before choosing a platform or design, it's essential to understand what differentiates a simple online store from a truly high-performing one. Catalog architecture, mobile experience, conversion strategy, organic search engine optimization (SEO), and brand perception play a central role in the success of an e-commerce project. We have detailed these fundamentals in our comprehensive guide dedicated to online sales sites in France, to help brands build a store truly designed to sell.
Why a specifications document is the real 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 essential elements are hidden in what's 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 framed 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's 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 document therefore begins with your business objectives, not with a list of features. A site built to drive acquisition does not look like a site built to maximize repurchases. A site aiming for margin is not managed like a site aiming for volume.
Describe your main objective in simple words: increase turnover, reduce reliance on marketplaces, improve profitability through direct sales, build a customer base, launch a range, open a new country. This sentence will serve as your compass to arbitrate the rest.
Then, specify how you will measure success. The right level of monitoring is not "measure everything," it's "measure what guides your decisions." An average basket, a conversion rate, a payment abandonment rate, a return rate, a proportion of recurring customers: these indicators already help a lot. They prevent you from judging the site based 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 conditions your navigation, your filters, your SEO pages, your merchandising, and even your customer service.
In the specifications document, describe your catalog as a system. How many actual references? How many variants per product? Do you have customizable products? Options that change the price? Stock or preparation constraints? These elements dictate how product sheets are built and inventory managed.
Also, specify your content standard per product sheet. An effective e-commerce product sheet is not just 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 clutter.
Then, formalize your strategy for packs and recommendations. Do you want to offer bundles, sets, 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 customer vocabulary, not your internal vocabulary. A "material" or "format" filter is useful, but a "usage" or "need" filter is often even more so. Effective search saves the visitor time and increases the store's revenue.
Customer journey: essential pages + mobile-first UX
The majority of e-commerce sessions happen on mobile, and the majority of friction comes from a "adapted" rather than "designed" journey. Mobile-first doesn't mean "smaller version." It means: clear reading, simple thumb actions, a neat information hierarchy, and reassurance present at the right moment.
In your specifications document, 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, deadlines, and delivery costs? When do they register, and why? This narrative highlights the steps in the decision-making process.
Certain pages are obviously essential (homepage, categories, product pages, cart, payment, trust pages), but effectiveness lies in the sequence. A product page, for example, must create desire, 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 live, keep this guide handy to improve your conversion rate. It will help you prioritize optimizations that have the most impact.
Payment, delivery, returns, taxes: rules and edge cases
This is the most "operational" part of the specifications document, and paradoxically the easiest to write. Why? Because this is where the edge cases live. And that's precisely what creates delays and additional costs if you discover them too late.
For payment, describe the essentials for your market and target. Depending on the country, expectations are not the same. Also clarify the rules: payments in installments, deferred payments, B2B with validation, or quote management. The goal is for the purchase journey to match the reality of your customers.
For delivery, go beyond "we will deliver everywhere." Where do you ship from? Which zones? Which carriers? What are realistic lead times? How are fees calculated? What happens if a basket contains a heavy product, a fragile product, or a pre-order product? An effective e-commerce site is often one where delivery is understood, not guessed.
For returns, be clear. Deadline, conditions, who pays, refund or credit, exchange or not. A readable 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 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 document, start with the architecture. Define your main categories and the logic of sub-categories. 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 content consistent with customer search.
If you are migrating or redesigning an existing site, the redirect plan is non-negotiable. It protects your traffic, your rankings, 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're optimizing 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 document must define what you want to measure to manage: product visibility, additions to cart, payment initiations, 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 consider 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, customer service
An e-commerce site is not an isolated project. It integrates into your daily operations: inventory management, order preparation, invoicing, customer support, email marketing, and sometimes marketplaces and points of sale. The earlier you clarify these interactions, the more stable and easy to manage your site will be.
Start by identifying the single source of truth for inventory and catalog. If your inventory lives somewhere other than in the online store, you need to define how it syncs and how often. Late stock-outs 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 journey: 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 reduces conversion, increases acquisition costs, and degrades the mobile experience. Quality, on the other hand, is not just about "it works." It is proven by structured testing.
In your specifications document, 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 smooth launch from a painful one.
Also consider accessibility and readability. Contrasts, text sizes, clear buttons, consistent navigation. This is not a luxury; it is a way to reduce friction for everyone.
Planning & budget: how to estimate (MVP vs V2)
A realistic budget is built on a clear scope. Without a specifications document, you get either a vague quote or an overly optimistic one. With a specifications document, you can estimate the project in versions.
The MVP is not a "discounted" site. It's a site that perfectly covers the essential scenarios for proper selling: clear catalog, fluid mobile journey, reliable payment, transparent delivery, healthy SEO foundation, and usable tracking. V2 then follows, fed by data: more advanced bundles, automations, content enrichment, conversion optimizations, additional integrations.
In the specifications document, write 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
A good specifications document 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, assumptions, deliverables, and method.
Send the document, then explicitly request 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 opt for 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 future 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
To conclude, here is a simple framework that you can copy and paste. The idea is not to produce a tome, but a clear document that aligns your objectives, scope, and constraints.
1) Context and objectives. Explain your activity, 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, stock management, and the expected content level on the product sheets.
4) Customer journey. Narrate the ideal visitor journey, especially on mobile, and specify reassurance points.
5) Payment, delivery, returns, taxes. Write down the rules and edge cases that your store must handle unambiguously.
6) SEO. Establish the architecture, priority pages, content strategy, and, if necessary, the redirect plan.
7) Tracking. Define what you want to track and how you will use this data for management.
8) Integrations. List the tools to connect and clarify the single source of truth for inventory 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, that can be managed, and that can evolve without rebuilding. The specifications document is the framework that enables this success. If you do it well, you save time, avoid surprises, and maximize your chances of having a high-performing store from the first few weeks.
