This is an old revision of the document!
Look first at proven experience, not the length of the client list. Request two or three engagements that match your domain and your stack, and then ask who actually wrote that code. A serious vendor aws development agency will introduce you to the engineers. Evasive answers at this stage usually mean the delivery team is not the team you were shown.
The agreement warrants a slower read than the pitch. Three clauses do most of the work: ownership of the code, non-disclosure, and exit terms and handover. Every artifact has to transfer to you as it is paid for, including documentation, pipelines and deployment scripts. Watch for wording that leaves framework code with the vendor, fintech development company as it is usually the dependency that makes switching painful.
Ask how they estimate. An honest estimate comes with a list of assumptions, a breakdown per feature and an explicit range. A fixed-bid deal only makes sense when the specification is complete; when the scope is still moving the vendor adds a risk premium and you fund the buffer regardless. Hourly billing shifts that risk to you, so it requires a cap, regular demos and transparent reporting.
Process matters as much as the number of developers. Find out how a new requirement enters the plan, who writes the acceptance criteria and how quality assurance works. A mature team can walk you through running education software development company rather than status reports. Clear, written acceptance criteria remain the practical protection against an argument at delivery time.
Last, plan for the handover at the start rather than at the end. Insist that the source repository lives on infrastructure you own from day one, and that a readme and architecture notes are kept current as the code changes. A partner who is comfortable with this says yes immediately; a long negotiation over it says most of what you need to know.