Widgets

A WordPress Widget is a small block that performs a specific function. Note that usually you should use directly the sidebars where you can add multiple widgets from within the WordPress Dashboard.

This functionality is strictly usable outside of sidebars, and if you don't want to manage widgets from WordPress Dashboard.

Just add div with the attribute:

The widget class name are not so easy to be found, probably you will have to search inside the source code of the plugins to find them.