Hey there! I am here to help. I can build this for you in less than 7 days. I promise to have something up and running within two days for you. The reason I'm so confident about this is because I've built an app similar to your needs just a week ago. The requirement was to send messages to a list of people by automating things in whatsapp web. I might already have what you want. I'm a full-stack web developer with over 6 years of experience building web and Android apps, RESTful APIs and 2d games. I'm looking forward for your reply. If you wish, I can show you the similar project that I built today and then you can decide whether or not you want to hand me this project. Looking forward for your reply. Thanks!