The single largest cost driver is never the choice of framework — it is almost always how much is still undecided. Every open question in the specification turns into padding in the estimate. A vendor that has no visibility into what happens on the unhappy path has to assume the worst. Spending a week on a discovery phase can cut the total by far more than any rate negotiation.
Connections questions to ask a software development company other systems are the next major multiplier. A feature that touches only your own data is low risk; the same feature wired into a payment provider difference between nearshore and offshore development a CRM is a different problem. The unknown sits in the third party: rate limits and sandbox access, long certification processes, inconsistent data. Ask each bidder to list every external system, because that is where the numbers slip.
Non-functional requirements can easily double the number. An application used by twenty people costs far less than the same functionality handling public traffic. Compliance work, uptime targets, scalability, audit logging and accessibility each add real engineering time. Put them in the brief or expect them priced as extras.
The team you are quoted matters a great deal. An hourly rate reveals almost nothing on its own: one senior developer at twice the price frequently turns out to be cheaper overall than two juniors who need constant review. Also ask which roles are billed: coordination, quality assurance, release engineering and UX design are real work, but they must be itemised.
The quoted figure is never what you will actually spend. Budget for infrastructure, paid APIs, monitoring and an ongoing support budget each year. A common working assumption says that edtech software development in active use needs a noticeable fraction of the initial investment every year in fixes, updates and small changes. Treating the launch as the finish line remains the classic mistake.