The largest difference between Code Anthem and TopCoder is that Code Anthem ranks you between 0-10 compared to other programmers, whereas TopCoder is a never-en

The largest difference between Code Anthem and TopCoder is that Code Anthem ranks you between 0-10 compared to other programmers, whereas TopCoder is a never-ending point system that rewards average programmers for spending more time on the site. While certainly TopCoder is used by a fair number of people, I've never met a professional programmer "in the wild" that used it. The dollar prizes are actually a disincentive to well-paid programmers who can make that money guaranteed doing consulting, rather than throw their name in the hat in a contest.