Hiring in-house buys you the deepest product knowledge. The engineers learn the business domain over months and years, and that knowledge stays in the building. The cost comes in the form of slow hiring and fixed overhead: recruiting a strong engineer takes months, getting someone productive adds more time, and the payroll carries on regardless of workload.

Full outsourcing implies the vendor owns delivery: the provider staffs the team, they manage the day-to-day work, and the provider carries the risk of missing the date. This works well when the work is a defined project and your side has an available product owner. It fails when nobody on your side owns the product, because an external team cannot invent your business rules.

Team extension sits between the two: you rent capacity but keep the management yourself. It is fast — a suitable engineer can start far sooner than a new hire — and the commitment ends when the work does. The catch is that your engineering managers must have the capacity to direct the work. If that capacity is missing, you end up paying for effort with no owner.

In the real world, these models are combined. A frequent arrangement holds architecture, product decisions and core domain code in-house, while an outside vendor global software development company handles the parts that are bounded and specifiable. The line is simple enough: retain what differentiates you, and contract out what is well understood.

Three simple questions generally decide the matter. First: is the system the product itself, or internal plumbing? Second: custom ecommerce development how long does the work continue — months or years? Last: who will maintain it in two years? Work through them with real answers and the model usually chooses itself.