VistaSwitcher - VistaSwitcher is an elegant and powerful task management utility for Windows OS.
Switcheroo - The simplest and fastest ALT-TAB replacement.
Contexts - Switch between application windows effortlessly — with Fast Search, a better Command-Tab, a Sidebar or even a quick gesture. Free trial available.
picom - A lightweight compositor for X11 (previously a compton fork).
Witch - Welcome to the world of W. i. t. c. h.
AltTabAlternative - Alternative application for Windows' native task switcher (Alt + Tab).