Customizing the messenger
You can use the API to specify a name and email that will be used to pre-fill the live chat form and contact form. This allows you to pass the information without requiring the customer to enter it manually. It makes sense to do this if you already know who the customer, for example when they are logged-in to your website.
Sometimes, you want to have a more prominent launcher or have the launcher appear at a certain spot on your website. For this you can create your own custom launcher button that can open the messenger when clicked using the API methods.
API enables you to hide the default messenger launcher. You might want to hide the launcher and only show it in certain cases. Or perhaps, you need to hide the launcher because you're using your own custom launcher.
See the full selection of available methods and code samples to help you get started on the Messenger API page.