Works well. You can customize the date/time display format. I use H:mm ddd D MMM YYYY as the format, which displays something like:

20:33 Thu 22 Sep 2022
21:33 Thu 22 Sep 2022
1:33 Fri 23 Sep 2022

after each city's/country's name.

It would be nice if all elements (day name "Thu", hour "1" or "20", month "Sep", colons :, spaces, etc.) lined up neatly in columns. I could essentially get the same result if I had the option of changing the font to a monospaced font (because then I'd just have to also change the H to HH to have all elements line up neatly).

A second change that I think would improve this addon would be to have the date/time text be selectable/highlightable so that I could copy it to the clipboard. Currently, attempting to select the text instead lets you drag/move/rearrange that row up/down to a new position. Often in many webpages (like YouTube playlists), the triple bar ≡ symbol is placed at the very front/end of each row and you hold left-click on ≡ to rearrange/move that row up or down. This way, all other parts of the row (i.e. other than the ≡ symbol) can be interacted with in the usual way (or other ways).

5 STARS - From Nobody! ;)
Great app, out of the way at the Top or Bottom of my screens, very handy, I trade the NY Stock Market, so when it opens its 1.30am here in Auckland, NZ, and now I know down to the second when it's opening and closing.
Thanks for a neat app.
Cheers Kev
www.Nobody.ooo

Wyświetla tylko ikonę którą trzeba kliknąć. Gdyby mógł wyświetlać tylko jeden zegar, ale jako zegar to byłoby doskonale.
Rozwiązanie ze status barem jest do bani bo zabiera miejsce.

The set clock time zones display only on the current tab page, otherwise it displays the default hongkong etc time zones. Moreover, the long date format is not inherited by all tabs, only for the current set tab page and so all other tabs show only the country flag without clock. Not very useful for multi tab browsing. (Firefox under Linux Leap on MacBook Air)

What an awesome add-on. I work with teams across different time zones, this add-one has been great! i can customize it and add it to my bookmark toolbar, it is always there for a quick glance. And i can also customize the date format! wonderful!

In the old versions (around the time of FireFox 42-49) you could choose to only show country flags or flags + text on the bottom bar.
Now it only seems to be possible to have the last (flags + text).

Is there still an option to only show country flags which I do not see?

Just like Upjohn's review It is a great addon. Unfortunately, recently it stopped working correctly. It shows wrong time for all time zones.
In my case the hours work correctly, but minutes are frozen on :04 minutes, and never change.
[UPDATE]
Have discovered that I inadvertently created the issue by incorrectly setting a custom date and time format. Now the extension works as described.

It's a great addon, very useful one. Unfortunately, recently it stopped working correctly. It shows wrong time for all time zones.

Hours work correct, but minutes are frozen on :03 minutes, and never change.

Superb on Waterfox, hit and miss on Firefox 94 or later.

Waterfox still has the Status Bar, so FoxClocks sits nicely above it and works 100% of the time. In Firefox 94, however, many sites display over the top of it, so it is a bit of hit and miss (examples flashscore.co.uk, marketscreener.com). With others, on Firefox, it displays but when you scroll up (and sometimes down), it disappears (example fintel.io). It has not been updated for a year, (Oct-2020), so maybe that's the reason.

Just what i needed, great addon 5/5 , cheers!