The core principle is simple: build what differentiates you, buy everything else. At org scale the decision is less about a single tool and more about where you choose to spend your scarce engineering capacity.
A decision framework
BUILD when:
- It is core to your competitive advantage
- No adequate solution exists, or yours must be materially better
- The capability must evolve constantly with your product
BUY when:
- It is a commodity (auth, payments, email, observability)
- A mature vendor solution exists and fits well enough
- Time-to-market matters more than control
Weigh , not just license price: integration, maintenance, hiring, and opportunity cost of the engineers not working on your product.
