Time.Is is a website where they tell that they show the world's most accurate web time in the world. They don't use your local computer time to show the current time, their time is synchronized to atomic clock time, their time is adjusted to DST (Daylight Saving Time) even if your computer clock doesn't. if your computer time is incorrect then it will tell you how much fast or slow your time is.
They will auto detect your country and city using your IP address and will show you the time accordingly. If you want to know the time of different country or city then you can search using their search (Enter location) box and know time of 7 million locations around the world, you will also get to know Sunrise, Sunset, Day length, Time zone offset, Time zone, Latitude, Longitude, Population, etc. of that location.
They also have a calendar, map (by default it will open to your current location using your IP address), compare time of different location by entering the name those cities/countries you would like to compare with.
Customize Time.Is page according to your need, for instance you can change format of date and time will appear, change font, change Black on white or White on black and you can also export your customization to different browser or computer.
If you want to embed it on your blog or website then you can use their widget or use this URL http://time.is/just in an iframe tag to embed or use the below code and change width and height according to your need.
Website : http://time.is/