A quote that comes back within a day is a warning, not a service level. An experienced provider responds with questions first: about users and volumes. A provider that quotes with no clarification is simply pricing a guess, and that guess will be corrected later — and you will pay for it.

Watch for any distance between the engineers on the sales call and the people who will code. Request the names and CVs of the actual team in the statement of work, with a clause that requires notice before anyone is swapped. A provider that talks only about a pool of resources and refuses to name people is keeping the option to staff you with whoever is free development estimate.

Insist on commit-level visibility from day one. A team that hands over code only at milestones is asking you to accept a black box. Visible commits reveal how many people are really working far better than a slide deck. This extends to the build and deployment setup: if there is no pipeline, quality claims remain nothing more than words.

Loose phrasing around code ownership is not an oversight. The contract must state explicitly that the code, designs and documentation belong to your llm development company on payment. Check also which is better rest or graphql country's law applies and the milestone terms: a large upfront payment with nothing due in return for weeks removes the only leverage you have.

Last, examine communication. Confirm how much working-time overlap you will share with your timezone, who answers questions and how quickly. Four hours of overlap is usually enough; none at all turns a five-minute question into a lost day. Sloppy written English in the sales phase will not improve once the work starts.