The biggest cost driver is never the technology stack — it is almost always unclear scope. Every ambiguity in the brief is converted into padding in the estimate. A vendor hire ai developers that cannot see what happens on the unhappy path will assume a pessimistic case. Investing a few days in requirements work can cut the final cost by far more than negotiating the rate.
Third-party integrations are the second big multiplier. A feature that touches only your own data is low risk; the same functionality wired into a legacy ERP is a different problem. The cost hides in the other system: poor documentation, long certification processes, inconsistent data. Ask each bidder to list every external system, as that is where the numbers slip.
The requirements nobody writes down silently change the estimate. An application used by a small internal team has almost nothing in common with the same idea serving public traffic. Compliance work, uptime targets, scalability, data retention rules and localisation add real engineering time. State them early or else expect them to arrive later as change requests.
The team you are quoted changes the arithmetic. A day rate says almost nothing on its own: a senior engineer at a premium rate is often cheaper per delivered feature than two juniors who require supervision and rework. Check too what else appears on the invoice: project management, testing, DevOps and design have to be done by someone, but they should be named rather than hidden inside a blended rate.
The quoted figure is rarely what you will actually spend. Plan for infrastructure, third-party licences, observability and an ongoing support budget each year. A useful planning figure says that software development companies in qatar in active use needs a noticeable fraction of the initial investment annually in fixes, updates and small changes. Leaving it out of the budget is the classic mistake.