The biggest cost driver is never the choice of framework — it is uncertainty. Each unanswered question in the brief turns into padding somewhere in the quote. A team that cannot see what happens on the unhappy path has to assume the more expensive option. Spending a week on a proper discovery frequently cuts the final cost far more than haggling over hourly rates.
Third-party integrations remain the second big multiplier. A feature that touches only your own data is easy to estimate; the same screen wired into a legacy ERP is not. The unknown sits in the third party: rate limits and ecommerce software development company sandbox access, long certification processes, fields that mean something different on each side. Ask each bidder to price integrations separately, as that is where the numbers slip.
The requirements nobody writes down quietly rewrite the number. An internal tool used by a handful of staff costs far less than the same idea handling a hundred thousand nearshore vs offshore outsourcing users. Audit and compliance requirements, availability guarantees, scalability, traceability and multi-language support add real engineering time. Write them down at the start or you can expect the estimate to move later.
The mix of people behind the number changes the arithmetic. A rate card reveals little on its own: a senior engineer at twice the price frequently turns out to be cheaper overall than two inexperienced developers who need heavy code review. Check too which is better laravel or symfony roles are billed: coordination, QA, infrastructure work and design are legitimate costs, but these should be named rather than hidden inside a blended rate.
The quoted figure is rarely the full cost of ownership. Budget for hosting, third-party licences, logging and alerting and an ongoing support budget each year. A reasonable rule of thumb holds that a live system needs a noticeable fraction of the original budget annually in fixes, updates and small changes. Treating the launch as the finish line is the classic mistake.