WhatsApp Auto-Reply Bot Setup

I need a simple WhatsApp chat bot that sends a custom greeting the moment a new message arrives. No message forwarding or data collection—just a clean, automated “hello” that feels personal.

Scope of work
• Connect the bot to my existing WhatsApp Business number (API, Twilio, or another reliable method—whichever you recommend).
• Configure a single custom greeting message that fires automatically on every first inbound message in a thread.
• Supply clear, step-by-step instructions so I can edit that greeting later without touching code.
• Test end-to-end to confirm users always receive the greeting instantly.

Please build with widely supported tools, keep the setup straightforward, and hand over any required keys or configuration files so I can maintain the solution myself.