Virtual WhatsApp Multimedia Message API

I need a straightforward API that lets a virtual WhatsApp number push out multimedia messages—specifically images and videos—on demand. The sole focus is outbound traffic; the service does not have to handle incoming chats or web-hooks beyond standard delivery receipts. Because other developers will be plugging this into their own stacks, the interface must be clean, well-documented, and language-agnostic.

Core behaviour
• Accept a destination number, media file (image or video) or hosted URL, optional caption, and immediately dispatch the message through the virtual WhatsApp line.
• Return a JSON response that confirms submission and exposes a unique message ID plus delivery status endpoint or callback.
• Provide a lightweight authentication method (token or key passed in headers) so it can be embedded in server-to-server calls without exposing credentials in client code.

What I expect to receive
1. Source code for the API (any mainstream language is fine as long as setup instructions are included).
2. Postman or cURL collection that demonstrates a successful text-plus-media send.
3. A concise README that covers environment variables, media size limits, rate limits, and error codes.
4. A short demo video or live sandbox proving a real WhatsApp delivery from the virtual number.

If the above works end-to-end—upload, send, receipt confirmed—the job is done.