Send the same 1 WhatsApp message to multiple numbers using Quick WA.
File to WA
Sending 1 different WhatsApp message to different numbers using Excel file
How to send 1 WhatsApp message in bulk according to a schedule that has been made to many numbers or contact groups with the same WhatsApp message.
Send different WhatsApp messages to many numbers with different date and time schedule settings.
Unofficial Whatsapp API:
Tutorial on how to send WhatsApp messages with PHP.
Integrate your system/application with the Whatsapp API, to send OTP notifications, invoices, reminders to your customers.