Hiring in-house gives you long-term retention of knowledge. The people absorb your customers and your data model in a way no external team will match, and that knowledge sits inside the reactjs app development company. The cost comes in the form of time and rigidity: hiring well routinely takes several months, onboarding adds several more weeks, and the cost carries on through the quiet quarters.
Handing a project to a vendor is the arrangement where an external team owns the outcome: they staff the project, they manage the plan, and they absorb the delivery risk. This fits well when the outcome can be described and there is someone who can make decisions quickly. It breaks down when nobody on your side owns the product, because the provider cannot invent your business rules.
Hiring individual contractors falls in the middle: you rent capacity and keep the management on your side. The main advantage is speed — a suitable engineer can start almost immediately — and it winds down as quickly as it ramped up. The trade-off is that your engineering managers have to have the capacity to direct the work. Without that, you are paying for effort with no owner.
In practice, the models mix. A common pattern holds architecture, product decisions and core domain code inside the company, while a partner takes on peaks, well-defined modules or affiliate marketing platform development work. The rule is easy to state: retain what differentiates you, and outsource what is well understood.
Three simple questions resolve most of these debates. First: is this software central to how you make money, or a cost centre? Second: how long will you need this capacity — months or years? Last: who owns it outsourcing services once the vendor leaves? Answer these three honestly and the model is normally clear.