Very simple Whatsapp bulk message sender script

I need a developer to create a very simple Whatsapp bulk message sender website and mobile app with number validator (which will tell if a phone number is registered on whatsapp or not) & Whatsapp group contacts extractor (which will simply make a text file of all phone numbers which are member of a whatsapp group / community).

First you can make a website for this and then convert javascript code to mobile app using Frameworks like Ionic or Capacitor or with webview.
A user can use multiple phone numbers to send bulk whatsapp messages
This app will also send 1 ad message attached with user’s original message to all non paying free users and users who buy a subscription plan will get ad-free experience.