Build vs. Buy Decision Framework

A rigorous build-vs-buy framework evaluates five dimensions: (1) Competitive differentiation—if core advantage, build; if supporting function, buy; (2) Total cost of ownership—building includes maintenance, security, and engineering opportunity cost, not just development; (3) Time to value—buying is typically 3-10x faster; (4) Customization need—if >40% customization is required, building may be cheaper long-term; (5) Strategic control—if vendor lock-in risk is unacceptable, building preserves autonomy. Initial development is only 20-30% of built solutions' lifetime cost; the remaining 70-80% is maintenance.

When to use it

When engineering proposes building something available as a product. When evaluating maintaining custom tools versus switching to commercial alternatives. When a vendor product requires extensive customization. When making any significant technology capability decision.

How it can help

For engineering leaders, this transforms gut-feel decisions into structured analysis. Score each dimension and let scores guide the choice. The most common mistake prevented: 'just build it'—engineers prefer building, and without a framework this leads to custom solutions for commodity problems. For startups, the framework strongly favors buying everything except core product—every hour on non-core infrastructure is an hour not spent on what matters. The 20-30% initial cost finding is the most important number to internalize.