I need a desktop application that does three things seamlessly: (1) verifies whether each mobile number in my list is registered on WhatsApp, (2) sends bulk messages once verification passes, and (3) runs natively on both Windows and macOS with the same intuitive graphical interface. Core workflow • I will supply contact numbers by uploading a CSV or Excel file. • The app should instantly flag non-WhatsApp numbers so no message credits are wasted. • For verified users, I must be able to broadcast plain text as well as images and videos. • A built-in scheduler lets me set future send times instead of pushing everything live at once. Interface & usability A clean GUI is critical—think drag-and-drop file import, progress bars for verification and send status, and simple tabs for composing messages, scheduling, and viewing logs. No command-line workarounds. Deliverables 1. Installable builds: a signed .exe for Windows 10/11 and a signed .dmg/.app for the latest macOS release. 2. Source code and build steps so future updates are straightforward. 3. A short PDF or video walkthrough covering installation, file-format requirements, and message scheduling. 4. Error handling that cleanly reports failed verifications or sends. Acceptance criteria • 1000 mixed numbers processed in under 5 minutes on a standard laptop. • Message delivery confirmed (double-tick) for verified contacts. • Scheduler triggers messages at the exact minute set, regardless of OS sleep/lock status. Feel free to rely on WhatsApp’s official Business API, selenium-based automation, or another reliable approach—the method is up to you so long as it remains stable against WhatsApp updates and my accounts stay safe from bans.