Start with proven experience, not the length of the client list. Ask for two or php web portal development three engagements that resemble your stack, and then ask specifically whether those engineers are still with the company. A solid partner will introduce you to the engineers. Answers that name nobody at this stage usually mean the delivery team is not the team you were shown.

The paperwork warrants a slower read than the pitch. Three clauses do most of the work: assignment of intellectual property, non-disclosure, and notice periods and handover. Every artifact has to transfer to you once invoices are settled, including designs, scripts and infrastructure configuration. Be careful with wording that keeps framework code in the vendor's hands, as this is frequently the dependency that makes switching painful.

Find out how the estimate was built. A credible estimate arrives with the assumptions behind it, a breakdown per feature and build an mvp explicit range. A fixed price works only when the specification is complete; in any other case the supplier adds a risk premium and you pay for it anyway. Hourly billing moves the risk back to the client, so it demands a cap, regular demos and transparent reporting.

Process matters as much as team size. Find out how change requests are handled, who writes the acceptance criteria and what the QA setup looks like. A mature team should be able to show you running software rather than status reports. Acceptance criteria in writing remain the only reliable protection against endless rounds of rework.

Finally, consider the end of the engagement while the relationship is still good. Ask that the code repository stays on infrastructure you own from the first commit, and that a readme and architecture notes are kept current as the code changes. A provider confident in its own work says yes immediately; a long negotiation over it tells you quite a lot.