It is a tool to help you automate your marketing. It helps you in quickly sending messages to a large number of users. These messages are send one-to-one which means that your messages are guaranteed to be delivered unlike sending via Broadcast. The functionality is achieved with the help of automating the Web.WhatsApp.com platform.
This tool works by automating the Chrome Browser by a tool called Selenium. It uses a software programming language called VB.NET for importing a database of your clients. These numbers are feeded to the Selenium automation tool and it automates the sending of the messages.
There is a limit to the number of messages you can send. The daily limit is based on which tier your account lies in. Most of the accounts are in Tier 1 which allows your company to send messages to 1K customers per day. Your account updates automatically to tier 2 once you start sending messages regularly and after that, you are allowed to send messages to an even larger number of users.
Instead of sending bulk messages, you should try to send genuine messages to users that can help you in increasing your revenue. Because the tool can be easily customized as per the needs of the user.