Start with domain experience, not the length of the client list. Ask for two or three projects that match your technology stack, and then ask whether those engineers are still with the company. A solid partner will put you on a call with the engineers. Evasive answers at this stage generally mean the delivery team is not the team you were shown.

The agreement needs more scrutiny than the proposal. Three sections matter more than the rest: ownership of the code, vue js software development the NDA, and exit terms and handover. Everything produced has to transfer to you as it is paid for, together with documentation, pipelines and deployment scripts. Look closely at any clause that leaves framework code outside the transfer, as that is often exactly the piece that locks you in.

Ask where their numbers come from. A serious estimate arrives with a written set of assumptions, a task-level breakdown and a best case and a worst case. A fixed-price contract is only reasonable when the scope is genuinely frozen; when the scope is still moving the vendor adds a risk premium and you pay for uncertainty either way. Time and materials puts the risk on your side, so it requires a cap, regular demos and transparent reporting.

Process beats the number of developers. Establish what happens when the scope changes, who defines done and how testing is organised. A mature team will be able to walk you through a working build every one or common mvp mistakes two weeks. Acceptance criteria in writing stay your only real protection against endless rounds of rework.

Last, plan for the handover before it becomes urgent. Insist that the code repository lives in your organisation from the first commit, and that the documentation is refreshed in every sprint. A vendor with nothing to hide says yes immediately; a long negotiation over it tells you most of what you need to know.