Building a wedding planning app involves the integration of various features that streamline the planning process. First, you need to identify the key features such as budget planning, checklist, guest list management, and vendor search, among others. Then, hire a professional app development team who can bring your vision to life, considering both iOS and Android platforms for wider reach. It's important to focus on user experience, making the app easy to navigate. Lastly, ensure the app is tested thoroughly before launch to fix any bugs or glitches.