FSelector is a Ruby gem that aims to integrate various feature selection/ranking algorithms into one single package. Welcome to contact me (email@example.com) if you want to contribute your own algorithms or report a bug. FSelector enables the user to perform feature selection by using either a single algorithm or an ensemble of algorithms. FSelector acts on a full-feature data set with CSV, LibSVM or WEKA file format and outputs a reduced data set with only selected subset of features, which can later be used as the input for various machine learning softwares including LibSVM and WEKA. FSelector, itself, does not implement any of the machine learning algorithms such as support vector machines and random forest.