Clocker 4+

This is a great app. I work with clients and talk with friends across the globe and while the maths is simple, keeping track of timezones mentally can become quite taxing and mistakes get made. Naturally, I’ve tried out a few different apps and websites, but this app has by far the most intuitive UI out of everything I’ve tried. I seem to use it without thinking. “What’s the time right now in New York?”, I’m thinking, and I can click on one icon that is in a position that is always present on my screen in the OS X toolbar (without having to open up a browser, without having to search for an app in spotlight, etc) and I can see a list of the current time in the timezones that are of interest to me. It might sound like I’m giving too much praise here, but I feel like this is a beautifully designed app that perfectly executes everything that you need it to do and nothing more, nothing less.

One of the down sides of having a 49inch ultrawide monitor is that things like the clock are a pain in the neck (quite litterally) to look at, as they are so far to one side. With this little menu bar app, paired with Bartender, I have been able to put a clock right in the centre of my menu bar for perfect glanceabilty! I love it! So simple, but with some great features like calendar/reminder instragration, wold clock functionality and the ability to scroll the time across all set timezones to easily work out relitive times.
And its free! NICE!

Lets me add my own aliases for locations (great for naming colleagues/offices instead of "Europe/Bucharest") and it has a slider to easily visualise future times across all of your locations.

If you mark your local timezone/location as a "favourite", you can use the menubar display prefs section in Clocker's settings to make it match the default MacOS time/date. THEN you can remove the default time/date from your menubar and replace it with one that looks the same, but has a much more useful world clock when you click it.