The dominant factor is not technology — it remains uncertainty. Every ambiguity in the brief is converted into a buffer in the estimate. A vendor that has no visibility into what happens on the unhappy path will assume the more expensive option. Spending a week on requirements work can cut the total far more than negotiating the rate.

Connections to other systems tend to be the next major multiplier. A screen that writes to your own database is predictable; the same feature connected how to choose the right software development company a legacy ERP is another matter entirely. The effort lives in the counterparty: poor documentation, long certification processes, inconsistent data. Ask the estimator to list every external system, since this is where estimates break.

Non-functional requirements silently change the budget. An internal tool used by a handful of staff costs far less than the same functionality serving thousands of external customers. Audit and compliance requirements, uptime targets, scalability, vue.js vs angular audit logging and accessibility all add real engineering time. Put them in the brief or you can expect the free development estimate to move later.

The team you are quoted matters. An hourly rate says almost nothing on its own: an experienced engineer at a premium rate frequently turns out to be cheaper overall than two inexperienced developers who need heavy code review. Ask as well which roles are billed: delivery management, testing, release engineering and analysis are legitimate costs, but these should be named rather than hidden inside a blended rate.

The number in the proposal is not the full cost of ownership. Expect infrastructure, paid APIs, monitoring and a change budget for every year the software runs. A useful planning figure says that any production system needs a noticeable fraction of the original budget every year for updates, security patches and small improvements. Treating the launch as the finish line has always been the most frequent planning error.