Look first at relevant experience, not the length of the client list. Ask to see a couple of projects that resemble your domain and your stack, and then ask whether those engineers are still with the symfony web development company. A serious vendor is happy to connect you with the engineers. Evasive answers at this stage almost always mean the demo work came from somewhere else.

The paperwork warrants more attention than the sales deck. Three sections matter more than the rest: intellectual property assignment, the NDA, and termination and handover. Every artifact should transfer to you once invoices are settled, along with designs, scripts and infrastructure configuration. Watch for language that keeps reusable components with the vendor, because it is usually the part you cannot replace later.

Ask how they estimate. A credible estimate comes with the assumptions behind it, a breakdown per feature and an explicit range. A fixed-bid deal only makes sense when the requirements are stable and documented; otherwise the vendor adds a risk premium and you pay for uncertainty either way. A time-and-materials model shifts that risk to you, so it needs a cap, regular demos and custom kubernetes development transparent reporting.

How the work is run beats headcount. Find out how change requests are handled, who defines done and what the QA setup looks like. A team can show you running software development company in russia rather than status reports. Clear, written acceptance criteria are the practical protection against endless rounds of rework.

Last, plan for the day you no longer need this vendor at the start rather than at the end. Ask that the repository lives on infrastructure you own from day one, and that the documentation is refreshed in every sprint. A partner who is comfortable with this accepts it without argument; resistance at this point reveals quite a lot.