The biggest cost driver is never the technology stack — it is almost always unclear scope. Each unanswered question in the brief turns into a contingency in the estimate. A vendor that does not know the edge cases will assume a pessimistic case. Investing a few days in a proper discovery frequently cuts the overall figure much more than negotiating the rate.
Integrations tend to be another reliable source of cost. A feature that touches only your own data is easy to estimate; the same functionality talking to an old accounting system is a different problem. The cost hides in the third party: monolith vs microservices poor documentation, waiting on someone else's team, inconsistent data. Ask any vendor to price integrations separately, since that is where the numbers slip.
Non-functional requirements quietly rewrite the budget. A tool used by a handful of staff costs far less than the same idea handling thousands of external customers. Compliance work, high availability, load handling, traceability and accessibility add real engineering time. Write them down at the start or expect the estimate to move later.
Who actually does the work matters. An hourly rate tells you almost nothing on its own: one senior developer at a higher rate frequently turns out to be cheaper overall than a pair of junior developers who require supervision and rework. Ask as well which roles are billed: delivery management, testing, infrastructure work difference between laravel and .net analysis have to be done by someone, nearshore software development but they must be named rather than hidden inside a blended rate.
The number in the proposal is not the full cost of ownership. Plan for hosting, third-party licences, observability and a maintenance allowance annually. A useful planning figure holds that a live system consumes a meaningful share of the initial investment per year for updates, security patches and small improvements. Leaving it outsourcing germany out of the budget is the most frequent planning error.
