This application is to help users to send message using WhatsApp application without need to save the contact number. You might be facing issue where you want to buy something and you need to ask the seller about the price or to negotiate the price with seller BUT you need to save the seller phone number first before you can start sending the message.
This application will help you open WhatsApp message by entering phone number only. So you can ask the seller about the price, specification etc before you can confirm to buy.
This not necessary only to ask seller, but you can use this app in daily basis like asking you colleague, friends etc.