This is a small java program that lists the working proxy address for a given url(for NITW), similar program can be written in python + urllib.
There's a GUI and CLI version of the program. GUI version ain't stable, it has some threading issues.
As of now,code works for https url only,for http url all you have to do is change the value of a variable name URL. I didn't do that because I'm lazy.
For future, proxy address with lowest latency can be used to set the system proxy.