**UK Keyboard**  
*[see below for other languages]*

<kbd> Cmd ⌘ </kbd> <kbd> ` </kbd> 

<kbd> Cmd ⌘ </kbd> <kbd> Shift ⇧ </kbd>  <kbd> ` </kbd> to go the other way.

Left of z on a UK keyboard [non-shifted ~ ]

[![enter image description here][1]][1]

**Note:** This only works if all windows are in the same Space, not if they are spread over multiple Spaces, which includes fullscreen. To overcome this, use <kbd>Cmd ⌘</kbd><kbd>Tab</kbd> as usual and on the icon of the application you want to switch windows in press the down arrow key (with <kbd>Cmd ⌘</kbd> still pressed). Then use left/right keys to navigate to the desired window across spaces and desktops.

BTW, specifically in Chrome & Safari, but no other app I know of on Mac, <kbd> Cmd ⌘ </kbd> <kbd> (number) </kbd> will select individual tabs on the frontmost window.

*It also would appear that <kbd> Cmd ⌘ </kbd> <kbd> ` </kbd>  is yet another of those language-specific shortcuts; so if anyone finds any more variants, please specify for which language & keyboard type.*

*If anybody finds new combos for different languages, please check Keyboard layout here - [Apple KB: How to identify keyboard localizations][2] - & add that as well as which Input Source you use in System Prefs > Keyboard > Input Sources.  
Add a keyboard picture from the KB page too, if that would help.  
That will make it easier for future Googlers.*

Further info:  
You can change the keys in System Prefs > Keyboard > Shortcuts > Keyboard...  
though it doesn't list the reverse direction, it does still work when you add shift to that new combo. I tested by moving mine from <kbd> ` </kbd>  (and <kbd> ~ </kbd>) to <kbd> § </kbd> (and <kbd> ± </kbd>)


  [1]: https://i.sstatic.net/4IrTe.png
  [2]: https://support.apple.com/en-gb/HT201794