The dominant factor is never the technology stack — it remains uncertainty. Each unanswered question in the requirements becomes a contingency somewhere in the quote. A supplier that does not know the edge cases has to assume the worst. Putting two weeks into a discovery phase frequently cuts the total much more than haggling over hourly rates.
Integrations are the second big multiplier. A screen that writes to your own database is low risk; the same functionality wired into an old accounting system is a different problem. The effort sits in the third party: next js vs laravel performance poor custom software development company documentation, slow approval cycles, fields that mean something different on each side. Ask each bidder to price integrations separately, as this is where estimates break.
The requirements nobody writes down quietly rewrite the number. An application used by a small internal team costs far less than the same idea serving thousands of external customers. Security reviews, high availability, scalability, traceability and localisation all add real engineering time. Write them down at the start 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: vue.js development services an experienced engineer at a higher rate can be less expensive in the end than two inexperienced developers who need supervision and difference between rest and graphql rework. Check too who else is billed: delivery management, testing, DevOps and design are real work, but they must be named rather than hidden inside a blended rate.
The build price is never the full cost of ownership. Expect infrastructure, third-party licences, observability and a change budget each year. A useful planning figure holds that any production system consumes a recurring percentage of the original budget per year simply to stay current. Treating the launch as the finish line is the classic mistake.