WhatsApp Broadcast Automation Tool

I need a small, self-hosted tool that automatically sends scheduled or event-driven WhatsApp campaigns to my existing broadcast lists. Each campaign must accept both plain text and attached media (images or short videos) and push them out without manual intervention... (Budget: ₹600 - ₹1500 INR, Jobs: API, Automation, C# Programming, JavaScript, PHP, Python, Software Architecture, Web Development)