**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, or if any are fullscreen.** To overcome this for non-fullscreen window, 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. *To emphasise, This fails for any fullscreened windows, whilst continuing to work for any that are not.*

You can also achieve this by clicking the app's icon in the Dock - this is the only method that will also switch to fullscreen windows, the other methods will not.

*From comments* - You can check which key command it is for your language by switching to Finder, then look at the Window menu for 'Cycle through windows'...

[![enter image description here][2]][2]

BTW, specifically in Chrome, Safari & Firefox, 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.*

*Unfortunately, as of July 2021, Apple has changed this page, making it useless for our purposes:/*  
*If anybody finds new combos for different languages, please check Keyboard layout here - [Apple KB: How to identify keyboard localizations][3] - & 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>)

[![enter image description here][4]][4]

You can use the alternative of <kbd> Ctrl ⌃ </kbd> <kbd> F4 </kbd> [visible in the prefs window above] but that almost indiscriminately marches through every single open window on all Spaces, without switching to the correct Space each time. It's really not too useful unless you use a single Space, just included here for completeness.


  [1]: https://i.sstatic.net/4IrTe.png
  [2]: https://i.sstatic.net/qDgYW.png
  [3]: https://support.apple.com/en-gb/HT201794
  [4]: https://i.sstatic.net/P5MJ5.png