npm

xprop

Display properties and attributes of X11 windows and atoms.

brewmacoslinux
Try with needOr install directly
Source

About

Property displayer for X

Commands

xprop

Examples

inspect window properties by clicking on it$ xprop
show all properties of a specific window ID$ xprop -id 0x4a00001
get window class and name information$ xprop WM_CLASS WM_NAME
display root window properties$ xprop -root
find window properties by application name$ xprop -name 'Firefox'