The dominant factor is not the choice of framework — it remains uncertainty. Each unanswered question in the brief becomes a contingency inside the number you receive. A supplier that cannot see the exceptions and software development for fintech edge cases has to assume a pessimistic case. Investing a few days in a discovery phase often reduces the overall figure by far more than haggling over hourly rates.
Connections to other systems are the next major multiplier. A screen that writes to your own database is easy to estimate; the same screen connected to an old accounting system is not. The unknown lives in the counterparty: rate limits and sandbox access, long certification processes, inconsistent data. Ask the estimator to price integrations separately, education software development company because this is where estimates break.
Non-functional requirements quietly rewrite the budget. A tool used by a handful of staff costs far less than the same feature set serving public traffic. Compliance work, availability guarantees, ios aso agency load handling, traceability and localisation all add measurable effort. Write them down at the start or next js development services you can expect the estimate to move later.
The mix of people behind the number matters. A rate card reveals very little on its own: a senior engineer at a premium rate frequently turns out to be cheaper per delivered feature than two juniors who require constant review. Also ask what else appears on the invoice: coordination, quality assurance, DevOps and analysis are legitimate costs, but they should be named rather than hidden inside a blended rate.
The build price is not the full cost of ownership. Expect hosting, paid APIs, observability and a maintenance allowance annually. A common working assumption says that a live system needs a meaningful share of its original build cost annually in fixes, updates and small changes. Leaving it out of the budget is the most frequent planning error.