WhatsDirect is best tool for WhatsApp to send messages to any numbers those are not saved in your Contacts.
How it works?
1. Enter a number to which you are going to send message.
2. Type your text message and tap on send button.
3. This will take you to the official WhatsApp app then a chat window is created on WhatsApp with given number.
Note - This app or app developer is not associated with WhatsApp. WhatsApp is a registered trademark of WhatsApp Inc. You should follow WhatsApp terms & condition while sending messages through WhatsDirect App.
Links for download