Begin with proven experience, not the length of the client list. Ask for a couple of engagements that match your technology stack, and then ask who actually wrote that code. A solid partner is happy to connect you with the tech lead. Vague answers at this stage almost always mean you are talking to a reseller.
The agreement needs a slower read than the pitch. Three clauses do most of the work: ownership of the code, confidentiality, igaming web development and exit terms and handover. All the work product should transfer to you once invoices are settled, along with source code, designs and infrastructure as code. Be careful with language that keeps reusable components outside the transfer, since this is frequently the dependency that makes switching painful.
Ask where their numbers come from. A serious estimate is accompanied by a written set of assumptions, a task-level breakdown and a range rather than a single number. A fixed-price contract only makes sense when the specification is complete; when the scope is still moving the supplier prices the risk in and you pay smm services for startups it anyway. A time-and-materials model moves the risk back to the client, so it requires a sprint cadence, demos and a budget cap.
The delivery process matters as much as headcount. Ask how a new requirement enters the plan, who writes the acceptance criteria and how quality assurance works. A well-run team should be able to show you running software rather than status reports. Clear, written acceptance criteria remain the only reliable protection against an argument at delivery time.
Before signing, plan for the day you no longer need this vendor at the start rather than at the end. Require that the repository stays on infrastructure you own from the first commit, outsource node.js development and that a readme and architecture notes are kept current as the code changes. A vendor with nothing to hide accepts it consulting services without argument; hesitation here tells you most of what you need to know.
