Look first at proven experience, not the length of the client list. Ask for a couple of engagements that sit close to your domain and your stack, and then ask specifically which engineers actually built it. A serious vendor is happy to connect you with the people who would work on your project. Answers that name nobody at this stage generally mean the demo work came from somewhere else.
The contract deserves more scrutiny than the proposal. Three clauses do most of the work: ownership of the code, the NDA, and notice periods and handover. All the work product must transfer to you on payment, along with source code, designs and infrastructure as code. Look closely at wording that keeps so-called reusable libraries with the vendor, since that is often exactly the piece that locks you in.
Ask how they estimate. An honest estimate is accompanied by the assumptions behind it, swift ios development company a breakdown by feature or module and a range rather than a single number. A fixed price works only when the requirements are stable and documented; in any other case the vendor pads the number and you pay for uncertainty either way. A time-and-materials model puts the risk on your side, so it requires a cap, regular demos and transparent reporting.
The delivery process matters more than the number of hire dedicated developers. Establish what happens when the scope changes, who writes the acceptance criteria and how testing is organised. A team should be able to walk you through a live build at the end of each sprint. Clear, written acceptance criteria are the practical protection against the it outsourcing dubai-was-never-in-scope conversation.
Last, plan for the handover while the relationship is still good. Require that the repository sits on infrastructure you own from the first commit, and that documentation is written as you go rather than left to the end. A vendor with nothing to hide will agree quickly; hesitation here reveals a great deal.
