Look first at proven experience, not the length of the client list. Request a couple of engagements that sit close to your domain and is langchain a rag framework your stack, and blockchain development outsourcing then ask whether those engineers are still with the company. A solid partner is happy to connect you with the tech lead. Evasive answers at this stage usually mean you are talking to a reseller.

The contract warrants more scrutiny than the proposal. Three clauses do most of the work: ownership of the code, non-disclosure, and termination and handover. All the work product should transfer to you as it is paid for, along with designs, scripts and infrastructure configuration. Be careful with wording that keeps reusable components with the vendor, livewire vs alpinejs as it is usually exactly the piece that locks you in.

Ask how they estimate. An honest estimate is accompanied by the assumptions behind it, a task-level breakdown and a range rather than a single number. A fixed price only makes sense when the scope is genuinely frozen; in any other case the supplier adds hire a software developer risk premium and you pay for it anyway. Hourly billing shifts that risk to you, so it demands a cap, regular demos and transparent reporting.

Process matters as much as the number of developers. Find out how change requests are handled, who signs off on a feature and what the QA setup looks like. A well-run team can show you running software rather than status reports. Acceptance criteria in writing remain the only reliable protection against endless rounds of rework.

Before signing, think about the end of the engagement at the start rather than at the end. Require that the code repository sits on infrastructure you own from day one, and that documentation is written as you go rather than left to the end. A partner who is comfortable with this will agree quickly; hesitation here reveals a great deal.