POC - WhatsApp Scheduler Mobile App Development

I need a skilled mobile app developer to create an Android and iOS mobile application. This app will function as a scheduler, capable of sending WhatsApp messages at pre-defined times, even when the app is not open. Key Features: - Send a message on WhatsApp at scheduled time ( ex: every 5 min), it should be sending message even app is closed, or rebooted phone., but should stop on a button click or uninstall app - Use predefined messages within the app - A user-friendly interface for easy navigation Freelancer Requirements: - Proven experience in mobile app development for both Android and iOS - Previous work with scheduling or automation apps is a plus - Good understanding of integrating with third-party apps like WhatsApp Please note, the selection of predefined messages will not be part of this project scope. Instead, these messages will be hardcoded into the app. I am looking for a developer who can deliver a high-quality, reliable app.