DataPreparator is a free software tool designed to assist with common tasks of data preparation (or data preprocessing) in data analysis and data mining. DataPreparator can assist you with exploring and preparing data in various ways prior to data analysis or data mining. It includes operators for cleaning, discretization, numeration, scaling, attribute selection, missing values, outliers, statistics, visualization, balancing, sampling, row selection, and several other tasks. Data access from text files, relational databases, and Excel workbooks. Handling of large volumes of data (since data sets are not stored in the computer memory, with the exception of Excel workbooks and result sets of some databases where database drivers do not support data streaming). Stand alone tool, independent of any other tools. User friendly graphical user interface. Operator chaining to create sequences of preprocessing transformations (operator tree). Creating of model tree for test/execution data.