Thynkr Systems
How to Write a Software Development Brief That Gets You Accurate Quotes
If you've ever requested quotes from software development agencies and received estimates ranging from £30,000 to £250,000 for what feels like the same project, the brief is almost always the explanation. Agencies quotin
Custom Software Development
4 min read
If you've ever requested quotes from software development agencies and received estimates ranging from £30,000 to £250,000 for what feels like the same project, the brief is almost always the explanation. Agencies quoting that range are not all incompetent. They are responding to a document that leaves so much open to interpretation that they are essentially quoting different projects.
A well-written software development brief doesn't require you to be technical. It requires you to be clear about what you need, honest about what you don't know yet, and specific about how you'll measure success. Here is what that actually looks like in practice.Start with the problem, not the solution
The most common mistake in software briefs is jumping straight to 'we need a web application that does X, Y, and Z' without explaining why. The problem statement is the most important part of the brief — it tells agencies whether they understand your context, it surfaces alternative approaches you may not have considered, and it anchors all subsequent scope decisions to a real business need.
A good problem statement describes the current situation, the specific friction or limitation that makes it inadequate, and the business outcome you want to achieve by changing it. It does not describe the software. 'Our operations team currently tracks client onboarding manually in spreadsheets, which creates version control problems and means progress is invisible to senior management' is a useful problem statement. 'We need an onboarding management system' is not.Define users and their core journeys
Who will use the software, what will they be trying to do with it, and how often? This section of the brief is the most revealing for agencies assessing complexity. A system used by fifty internal staff who can be trained is very different from a public-facing platform used by ten thousand consumers with varied technical literacy.
You don't need to write detailed user stories at brief stage. You need to describe the two or three primary user types and the core tasks they will perform. 'A client manager who logs in daily to update onboarding milestone progress for active clients, and a senior manager who reviews a weekly pipeline dashboard without logging in to the main system' tells an agency a great deal about what they're quoting.Be explicit about integrations
Integration requirements are frequently the single biggest source of scope underestimation. If your new system needs to talk to your CRM, your accounting platform, your payment gateway, or your existing data warehouse, that needs to be in the brief — ideally with details of whether those integrations are well-documented modern APIs or legacy systems with limited connectivity options.
If you don't yet know all the integration requirements, say that explicitly. 'We know we'll need to integrate with Salesforce. There may be additional integrations we identify during discovery' is honest and helpful. It lets agencies quote a base scope while flagging integrations as a variable.Describe your technical constraints
Does your organisation have existing technology standards that the new system must comply with? Preferred cloud provider, mandated security frameworks, internal IT policies around data residency? If your organisation runs entirely on Microsoft Azure and has an IT policy requiring all new systems to be hosted there, that needs to be in the brief — because an agency that quotes a Google Cloud solution has wasted both your time and theirs.
Similarly, if you have an existing codebase that the new system needs to complement or integrate with, describe its technology stack. New systems built in Python may not integrate cleanly with a ten-year-old Java application without additional translation layers, and that has cost implications.Define what success looks like
A brief that includes measurable success criteria is substantially more useful than one that doesn't. You don't need a comprehensive performance specification at brief stage, but some indication of scale and performance expectations is genuinely important. 'The system needs to handle 500 concurrent users without performance degradation' is a design constraint that affects architectural decisions. 'It needs to be fast' is not.
You should also describe your timeline expectations honestly. Not because agencies will simply fit into them — some things take as long as they take — but because timeline pressure affects the resource model agencies will propose, which affects cost. A project that needs to be live in six months may require a larger team running in parallel to one that could be delivered methodically over twelve.State what you don't know
The section most briefs are missing is an honest account of what hasn't been decided yet. Open questions about scope, uncertain requirements, known risks. Agencies that see this section know they are working with a realistic client who understands how software projects actually unfold. It builds trust, and it allows them to propose a discovery or scoping phase to resolve the unknowns before committing to a fixed price — which is usually the right approach for complex projects.ThynkrSystems offers a no-obligation brief review for businesses preparing to commission software development. We'll tell you honestly what's well-defined, what needs more work, and where the risk of significant scope variance lies.