Whatsapp should send 1) Files. 2) Message.
But I do Not want to open whatsapp web.
Programmatically, it should send automatic.
You use whatsapp api.
I am Not sure, but may be : [login to view URL]
Or anything else, you can suggest.
It is Ok to use PHP Or node.js.
If you want to use anything else, let me know what.
Manually, currently I use below system to send message.
[login to view URL] is Sample Message