Flexible Statistics for Data Analysis toolbox (FSDA, http://rosa.unipr.it/fsda.html) is an open source statistical library providing a rich variety of robust and computationally efficient methods for the analysis of complex data, possibly affected by outliers and other sources of heterogeneity. It offers interactive tools for exploratory data analysis. It provides several state of the art robust estimation methods in regression, multivariate analysis, clustering and time series analysis. It offers also principled routines for the evaluation and calibration of clustering methods, based on the generation of synthetic data under controlled settings. FSDA is the results of the joint work of many researchers from different institutions, among which the University of Parma and the Joint Research Centre of the European Commission.