Start with proven experience, not the number of logos on the website. Ask for two or three case studies that resemble your stack, and then ask specifically whether those engineers are still with the company. An honest provider is happy to connect you with the tech lead. Vague answers at this stage almost always mean the delivery team is not the team you were shown.

The agreement warrants a slower read than the pitch. A few clauses carry most of the weight: intellectual property assignment, confidentiality, application support and maintenance services termination and handover. All the work product should transfer to you once invoices are settled, along with documentation, pipelines and deployment scripts. Watch for any clause that keeps reusable components in the vendor's hands, top node js development companies because it is usually exactly the piece that locks you in.

Ask where their numbers come from. A credible estimate is accompanied by a list of assumptions, a breakdown per feature and an explicit range. A fixed price is only reasonable when the scope is genuinely frozen; otherwise the supplier adds a risk premium and you fund the buffer regardless. Hourly billing shifts that risk to you, so it needs visible weekly reporting and a spending cap.

How the work is run beats headcount. Find out what happens when the scope changes, who writes the acceptance criteria and what the QA setup looks like. A well-run team should be able to demonstrate running software development cost rather than status reports. Clear, written acceptance criteria are the only reliable protection against the it-was-never-in-scope conversation.

Finally, consider the handover before it becomes urgent. Insist that the source repository sits in your organisation from day one, and that a readme and architecture notes are kept current as the code changes. A provider confident in its own work accepts it without argument; a long negotiation over it says a great deal.