Build vs Buy for IT Leaders

Every IT leader faces the same recurring question: should we build this ourselves or buy an off-the-shelf solution? It sounds simple, but getting it wrong can cost your organisation hundreds of thousands of pounds and years of wasted effort.

I have sat through dozens of these debates across different organisations. The pattern is always the same - engineering teams want to build, procurement wants to buy, and leadership wants it done yesterday. The reality is that neither option is universally correct. What matters is having a structured framework for making the decision well.

Why Build vs Buy Decisions Go Wrong

Most organisations get this wrong because they frame it as a binary choice. They compare the sticker price of a SaaS product against estimated development costs and pick the cheaper option. That approach ignores the total cost of ownership on both sides.

When you build, you are committing to ongoing maintenance, security patching, infrastructure costs, and the opportunity cost of developers who could be working on revenue-generating features. When you buy, you are committing to vendor lock-in, licensing escalation, integration complexity, and feature roadmaps you cannot control.

The question is never simply "which costs less?" It is "which approach creates the most strategic value while carrying acceptable risk?"

The Decision Framework

After years of navigating these choices, I use a five-factor framework that cuts through the noise.

1. Core vs Context

This is the most important question. Is the capability you need core to your competitive advantage, or is it contextual infrastructure that every business needs?

If the software directly differentiates your product or service, building makes sense. You need full control over the roadmap, the user experience, and the pace of innovation. No vendor will care about your specific market niche as much as you do.

If the capability is contextual - payroll, email, CRM, monitoring - buy it. Every hour your engineers spend reinventing solved problems is an hour stolen from genuine innovation. I have seen teams spend eighteen months building internal tools that a SaaS product could have replaced in a week.

2. Total Cost of Ownership

Calculate the genuine five-year cost for both options. For building, include:

• Developer salaries and recruitment costs
• Infrastructure and hosting
• Ongoing maintenance (typically 15-20% of initial build cost annually)
• Security and compliance obligations
• Documentation and knowledge transfer risk

For buying, include:

• Licensing fees with realistic growth projections
• Integration and customisation costs
• Training and change management
• Contract escalation clauses
• Exit costs if you need to switch vendors

Most organisations underestimate build costs by 2-3x and underestimate buy costs by 30-50%. Be honest about both.

3. Time to Value

How quickly do you need this capability? Building typically takes 6-18 months for anything meaningful. Buying can deliver value in weeks.

If there is a genuine competitive window or compliance deadline, buying gives you speed. You can always revisit the decision later. I have seen organisations lose market opportunities because they insisted on building the perfect solution rather than deploying something good enough now.

4. Team Capability and Capacity

Do you actually have the engineering talent to build and maintain this? Be brutally honest. Having developers who can build a prototype is not the same as having a team who can operate, scale, and secure a production system for years.

If building requires hiring specialists you do not currently have, factor that into your timeline and cost. In the current market, hiring experienced platform engineers or security specialists can take three to six months.

5. Vendor Risk Assessment

When buying, assess the vendor as thoroughly as you would a business partner. Consider:

• Financial stability and funding runway
• Customer concentration risk
• Data sovereignty and compliance posture
• API maturity and integration flexibility
• Contract terms around data portability

I have been burned by vendors who were acquired and had their products sunset within eighteen months. Always have an exit strategy before you sign.

The Hidden Third Option - Compose

The modern answer is increasingly neither pure build nor pure buy. It is compose - assembling solutions from APIs, open-source components, and managed services.

Platforms like AWS, Azure, and GCP provide building blocks that let you create custom solutions without starting from scratch. You get the control of building with the speed and reliability of managed services.

For example, instead of building a complete observability platform from scratch or buying a monolithic tool, you might combine Grafana for dashboards, Prometheus for metrics, and a managed logging service. You own the configuration and can swap components, but you are not maintaining the underlying infrastructure.

When to Build - The Checklist

Build when:

• The capability is a genuine competitive differentiator
• You have the engineering talent and capacity
• You need deep integration with proprietary systems
• Vendor options do not exist or are immature
• Data governance requirements make third-party processing unacceptable

When to Buy - The Checklist

Buy when:

• The problem is well-solved by existing products
• Speed to market matters more than customisation
• You lack the specialist skills to build and maintain
• The total cost of ownership favours purchasing
• The vendor ecosystem is mature and competitive

Making the Decision Stick

Once you have made the decision, document it. Write down the factors you considered, the alternatives you evaluated, and the assumptions you made. This serves two purposes.

First, it prevents relitigating the decision every six months when someone new joins the team and asks "why did we not just build this ourselves?" Second, it gives you a baseline to revisit when circumstances change. If your key assumption was that the vendor would maintain a specific pricing model and they double their rates, you have a clear trigger to reassess.

The Pragmatic Approach

The best IT leaders I have worked with treat build vs buy as a portfolio decision rather than individual choices. They build where it matters most, buy where it does not, and continuously reassess as the business evolves.

They also resist the sunk cost fallacy. If you built something two years ago and a superior product now exists at a fraction of the maintenance cost, migrating is not admitting failure. It is good technology leadership.

The goal is not to be right about every decision. It is to make decisions quickly, learn from the outcomes, and adjust. Build vs buy is never permanent - it is a strategy that evolves with your business.