An in-house team delivers long-term retention of knowledge. The engineers internalise your customers and your data model over months and years, and that accumulated context stays with you. The price shows up as a long ramp-up and fixed price software development costs: recruiting a strong engineer takes months, ramping up takes several more weeks, and the cost continues whether the roadmap is full or empty.
Handing a project to a vendor implies someone else is accountable for shipping: the partner staffs the team, they manage the process, social media marketing agency and the provider carries the delivery risk. The model works when the work is a defined project and your side has someone who can make decisions quickly. It breaks down when there is no one to answer questions, as an external team is not able to guess what the business wants.
Hiring individual contractors is the middle option: you rent capacity and keep the management in-house. It moves quickly — a matching profile can join far sooner than a new hire — and it scales down as easily as it scales up. The trade-off is that your technical leaders must have time for code review and planning. If that capacity is missing, the result is paying for effort with no owner.
In the real world, these models are combined. One durable pattern keeps the critical decisions and the core system with permanent staff, while a partner takes on discrete features, migrations or mobile clients. The principle is easy to state: retain what differentiates you, and contract out the well-trodden work.
Three questions generally decide the matter. First: is the system the product itself, or internal plumbing? Second: over what horizon does the work continue — one project or a permanent roadmap? Third: who will maintain it in two years? Answer these three honestly and the appropriate option usually chooses itself.