Time Zone Converter is described as 'Time and time zone converter. Readily tell the time anywhere in the world using frequently updated time zone database'. There are more than 25 alternatives to Time Zone Converter, not only websites but also apps for a variety of platforms, including Windows, iPhone, iPad and Android. The best alternative is timeanddate.com, which is free. Other great sites and apps similar to Time Zone Converter are World Time Buddy (Freemium), Time.is (Freemium), timee.io (Free) and FoxClocks (Free, Open Source).
FoxClocks is a Firefox/Thunderbird extension to display local times around the world in your status bar or any toolbar. Virtually all the worlds time zones are supported. FoxClocks also allows you to explore each time zone in Google Earth.
WorldClock shows you the time in different places over the world. Also included are the Swatch Internet Time, Julian Date and StarDate. You can also use it to synchronize the time with an atomic clock.