Machine learning and Data mining are becoming increasingly important in the recent years and have been successfully applied to solve a number of problems, especially in the areas of science and engineering. A variety of algorithms exist in the popular data mining tool ‘Weka’ to classify a given set of records into different classes. However, choosing the right classifier among them is a tricky task as the performance of a particular algorithm depends on various factors such as the application domain and the data set. In order to aid the researchers in comparing the performances of various classification algorithms in Weka, we have developed an online resource named Web-Weka using which one can compare a set of classification algorithms on a single data set on the fly and choose the right classifier for their study. The tool is available for free at www.mcr.org.in/webweka.