Start with the business problem, not a list of screens. What kind of user will use it day to day, with what frequency, and hire expert react native app developers what happens today? A vendor who grasps the purpose will suggest a cheaper route to it; a team that receives only a list of screens can only price exactly what you asked for.
Set out the scope as concrete flows: a walk through each important path. Just as important, write down what the first release deliberately excludes. A written out-of-scope list saves more disagreement later than almost anything else in the document. Indicate as well which parts are firm and which are still open — the difference changes the price, and hiding it helps no one.
Set out your constraints. These include the platforms and services involved, the data you already hold and its condition, compliance requirements, expected load, target platforms and infrastructure that is already decided. If there is a hard date, say why: a team can often rearrange the plan how to hire golang developers meet it, but only if they know it exists.
Write down what the word done means feature by feature. Acceptance criteria need not use any formal notation: a short paragraph stating what a user should be able to do is sufficient. This single habit shortens the review at the end by a surprising margin and removes the usual argument at handover.
Finally, ask for a specific format. Ask for custom app development an itemised estimate, the assumptions used, the main risks and an optimistic and a pessimistic figure. Take a broad range as a signal about the brief: it normally identifies exactly which requirement is unclear. At that point clarify that area and request a revised number — the second estimate will be much more reliable.
