A quote that comes back within a day should be treated as a bad sign. Any serious team will come back with questions first: about integrations. A vendor that commits to a figure before understanding the scope is probably working from a template, and hire senior node js the gap will be corrected later — on your budget.
Watch for a gap between the team in the pitch and the people who will code. Insist on the names and CVs of the actual team in the statement of work, with a provision that requires notice before anyone is swapped. A provider that only offers abstract roles and never names specific engineers is reserving its own flexibility at your cost.
Ask for the source repository from the start. A partner that shows code only at milestones expects you to trust a black box. Regular commits and pull requests show you the actual pace far better than a slide deck. The same applies to the build and php or python deployment setup: if there is no pipeline, promises about quality are nothing more than words.
Ambiguous wording in the contract around code ownership is rarely a formality. The document should state in plain terms that all outputs produced under it transfer to the client upon settlement of the relevant invoice. Look too at which country’s law applies and the milestone terms: a large upfront payment with no milestone tied to it eliminates any leverage you would otherwise keep.
Lastly, examine communication. Establish how many hours there will be with your timezone, who is expected to answer questions and on what response times. Four hours of overlap is usually enough; none at all stretches each small question into a day of delay. Unclear written communication in the sales phase rarely improves once the work starts.