How to write a brief for a software project: a brief that works

A high-quality brief for a software project determines whether a vendor can quote the project accurately, or whether the quoting process turns into a series of guesses. Companies often arrive with an idea along the lines of "we need an order management system" and expect a concrete quote – but without further information, a vendor can only offer a rough estimate, not a binding proposal. A good brief for developers isn't extra bureaucracy; it's a tool that saves both sides time and reduces the risk of misunderstandings during delivery.

This article describes how to prepare a brief for a software project so that a vendor can genuinely assess it – without you needing to be a technical expert. We'll look at the structure of a brief, concrete ways to phrase requirements, and the most common mistakes worth avoiding.

A software specification isn't just a formality before signing a contract. It's a shared reference point that both sides return to throughout the project – during quoting, architecture design, and testing the result. If the brief is unclear, the vendor fills the gaps with their own assumptions, which may not match what you had in mind. The result is usually additional questions, scope changes during development, and tension between client and vendor.

A precise brief, on the other hand, allows the vendor to:

• understand the context and goals, not just a list of features,
• estimate the technical complexity of individual parts,
• identify risks and open questions before development begins,
• propose a realistic approach instead of a generic quote.

The less room you leave for guesswork, the more accurately you can compare quotes from different vendors – and the easier it is later to assess whether the project was delivered as agreed. If you're weighing up several vendors, it's worth also reading how to choose a software vendor and what to ask when selecting one – a solid brief and choosing the right vendor are closely linked.

A working brief doesn't need to run to dozens of pages. What matters more is that it covers the right areas and is written from the perspective of the problem you're solving – not just as a list of desired features.

Project goal and context

The brief should open with a brief explanation of why the project exists. What problem it solves, who will use it, and what will change once it's done. For example: "We currently track orders in Excel, which causes duplicates and a loss of overview once we have more clients." This one sentence tells a vendor more than a technical specification of screens, because it explains the motivation behind the project – and lets the vendor propose a better solution than you originally expected.

Users and usage scenarios

Describe who will work with the system and in what situations. An internal employee processing orders has different needs from a customer shopping in an online store. If the system has several types of users (administrator, regular user, external partner), state this – it affects the design of both permissions and the interface.

Functional requirements

This is the core of the brief. Instead of a general "we need reporting", describe what data should be displayed, where it comes from, and who works with it. It's a good idea to order functional requirements by priority – what's essential for launch and what's "nice to have". This lets the vendor design a solution that addresses the core problem and push optional parts into a later phase.

Technical and integration constraints

State which systems your company already uses and what the new solution needs to connect to – accounting system, CRM, e-commerce platform, attendance system. If you're planning to connect several systems via an API, it's also worth reading an overview of approaches to connecting company systems and exchanging data – it will help you frame expectations for this part of the brief more clearly. Also mention constraints that aren't obvious from the outside: internal security policies, hosting requirements, or the obligation to support specific devices or browsers.

The quality of a quote depends directly on how specific the brief is. Vague phrasing forces the vendor to make their own assumptions, which can differ from project to project – which is why quotes from different vendors for the same "brief" are often hard to compare.

Besides concrete phrasing, it also helps to define acceptance criteria – that is, how you'll know a given feature is finished and working correctly. Even a simple sentence like "an order can only be created once all required fields are filled in" significantly reduces the room for ambiguity when the result is handed over.

You can picture the relationship between how specific the brief is and how many gaps the vendor has to fill in with follow-up questions like this:

This is an illustration of a general principle, not measured data – the exact impact depends on the specific project and its complexity. What ultimately influences the scope and complexity of development is described in more detail in the article on the factors that determine the scope and complexity of custom software development.

Even experienced companies make similar mistakes when preparing a brief. Knowing these patterns will help you avoid them in advance.

• The brief describes a solution, not a problem. If a company decides on a specific technology or screens in advance, the vendor loses the room to propose a more efficient approach.
• Requirements aren't prioritised. Without distinguishing what's essential from what's a "bonus", it's hard to assess what belongs to the core scope.
• Existing systems aren't mentioned. If the brief doesn't state what the new solution needs to connect to, the vendor can't estimate the complexity of integration.
• No project owner. A brief should have one person responsible for decisions – otherwise feedback during development gets scattered across several people with differing expectations.
• Expecting an exact price without details. A vendor can only offer a serious estimate based on a sufficiently described scope; the accuracy of a quote grows together with the accuracy of the brief.

A well-prepared brief is a starting point, not a final version. After receiving a brief, a serious vendor will usually ask follow-up questions, or propose an initial analysis phase during which the brief is refined into a form that can serve as the basis for both solution design and testing the result. How this kind of collaboration with a custom software vendor looks step by step is described in the article on the individual phases of custom software development.

If an AI component is also meant to be part of the project – for example, an automated agent working with your data – it's worth flagging this area in the brief in advance, since it affects the architecture of the whole solution. You'll find an overview of the factors that come into play in such a brief in the article on what influences the price and complexity of building a custom AI agent.

Before sending the brief to several vendors, it's worth going through it once more with fresh eyes – checking that it includes the goal, context, users, prioritised requirements, and known constraints. A brief like this makes it far easier to compare quotes and reduces the risk of major ambiguities surfacing during delivery. If you're not sure whether your brief is specific enough for an accurate quote, you can go through it together with the INTERFASE team in a non-binding consultation – or take a look at completed solutions in our references to see what the outcome of a similar process looks like in practice. Our experience with custom software development is also summarised on the custom development page.