Mariel Desailly

The single largest cost driver is rarely the technology stack — it remains how much is still undecided. Every open question in the brief turns into a contingency inside the number you receive. A supplier that does not know what happens on the unhappy path must assume the worst. Investing a few days in a discovery phase can cut the overall figure far more than any rate negotiation.

Connections to other systems are another reliable source of cost. A feature that touches only your own data is predictable; the same functionality talking to an old accounting system is another matter entirely. The cost sits hire developers in europe the third party: poor documentation, long certification processes, inconsistent data. Ask the estimator to price integrations separately, since that is where the numbers slip.

Non-functional requirements quietly rewrite the number. A tool used by a handful of staff costs far less than the same feature set handling thousands of external customers. Audit and compliance requirements, high availability, performance under load, traceability and localisation each add real engineering time. State them early or you can expect them to arrive later as change requests.

Who actually does the work matters. A rate card reveals almost nothing on its own: an experienced engineer at a higher rate can be cheaper per delivered feature than two juniors who need supervision and rework. Ask as well which roles are billed: delivery management, QA, DevOps and analysis have to be done by someone, but these should be named rather than hidden inside a blended rate.

The number in the proposal is not what you will actually spend. Expect hosting, subscriptions and licences, observability and a change budget for every year the software runs. A useful planning figure is that any production system needs a recurring percentage of its original build cost annually in fixes, web development company uk updates and docker development services small changes. Ignoring this has always been the classic mistake.