Applying the core-vs-context test
Ask two questions: does this capability differentiate us to customers, and do we hold proprietary data that makes our version better? Two yeses means core, consider building. Any no means context, buy or integrate.
The two-question test
Core capability both differentiates you and is powered by proprietary data. If a capability fails either test, a vendor will almost certainly do it better and cheaper than you can.
Differentiation and data are the two gates. A capability that differentiates you but uses only commodity data can usually still be bought and customized. A capability powered by proprietary data but that does not differentiate you is a support function, not a moat. Only when both are true, it sets you apart and your data makes it uniquely good, is building potentially worth the 15–30% annual maintenance tax and the talent risk. In practice, that is a short list for most companies.
Frequently asked questions.
Can a context capability become core later?
Yes, and that is why the integrate pattern is useful. Buy the capability now, keep your data portable, and if it later becomes a genuine differentiator you can invest in building the part that matters, without having wasted years building the commodity layer first.