Look first at domain experience, not the size of the portfolio. Ask for a couple of engagements that match your stack, rag system development and then find out which engineers actually built it. A serious vendor will introduce you to the people who would work on your project. Answers that name nobody at this stage usually mean you are talking to a reseller.
The contract warrants more scrutiny than the proposal. A few clauses carry most of the weight: assignment of intellectual property, the NDA, and termination and handover. All the work product has to transfer to you once invoices are settled, together with designs, scripts and infrastructure configuration. Look closely at any clause that keeps framework code in the vendor’s hands, because that is often exactly the piece that locks you in.
Ask where their numbers come from. A credible estimate comes with the assumptions behind it, a task-level breakdown and an explicit range. A fixed-bid deal works only when the specification is complete; when the scope is still moving the supplier prices the risk in and you pay for laravel or symfony uncertainty either way. A time-and-materials model puts the risk on your side, so it requires visible weekly reporting and a spending cap.
How the work is run matters more than team size. Ask how change requests are handled, who writes the acceptance criteria and what the QA setup looks like. A mature team will be able to demonstrate running software development company in dubai rather than status reports. Clear, written acceptance criteria remain the practical protection against endless rounds of rework.
Finally, think about the end of the engagement while the relationship is still good. Insist that the source repository lives under your account from day one, and that documentation is written as you go rather than left to the end. A vendor with nothing to hide accepts it without argument; hesitation here says a great deal.