AltTab is a Mac application that introduces a way to switch tabs similar to Windows Alt+Tab function, the difference being that it only allows you to switch between apps, not application windows.
Its interface consists of a main menu, with various tabs and nicely crafted icons. However, the icons lack color, but at least there are lots of customization options and even a few skin themes.
With AltTab, you are able to customize multiple functions. There's the option to switch between themes, modify the popup dimension, the size or icon size.
In case you want to add a delay before the display of the popup, you can do that too.
To start using the Alt+Tab function, you first have to set up the hotkey for this function. Then you'll be able to see all your active windows and simply start cycle between them using your chosen hotkey. The only con is that you can't close the apps from the popups.
In conclusion, AltTab is a cool Mac utility that provides a way to implement the Alt+Tab function on MacOS computers.