When you decide to build a stock trading app, many factors influence how much you will spend. There is no one standard cost. Instead, your budget depends on choices like the app’s complexity, platform, features, design, security, and team location. Some of the main factors are: Type of app : Are you building a simple buying/selling app or a richer platform with charts, analytics, and automation tools? Target platforms : Will the app be available on iOS, Android, web, or all t