The dominant factor is not the choice of framework — it remains how much is still undecided. Every open question in the specification is converted into a buffer inside the number you receive. A supplier that does not know what happens on the unhappy path has to assume the worst. Putting two weeks into a proper discovery frequently cuts the final cost far more than haggling over hourly rates.

Integrations tend to be another reliable source of cost. A screen that writes to your own database is predictable; the same screen connected to an old accounting system is a different problem. The effort sits in the other system: undocumented APIs, long certification processes, data that does not match your model. Ask the estimator to break integrations out as separate items, livewire vs alpinejs as 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 functionality serving public traffic. Audit and compliance requirements, top reactjs development companies high availability, scalability, traceability and accessibility add weeks of work. Write them down at the start or you can expect them to arrive later as change requests.

The mix of people behind the number changes the arithmetic. A rate card reveals almost nothing on its own: one senior developer at twice the price frequently turns out to be cheaper per delivered feature than a pair of junior developers who need heavy code review. Ask as well who else is billed: coordination, testing, release engineering and UX design have to be done by someone, but they must be visible in the estimate.

The number in the proposal is rarely the full cost of ownership. Expect infrastructure, subscriptions and licences, observability and a change budget annually. A reasonable rule of thumb holds that a live system needs a noticeable fraction of the initial investment annually for updates, security patches and small improvements. Ignoring this is the most frequent planning error.