<p>Dataplot is a free software system for data analysis, including characterization, visualization and modelling. It was developed in FORTRAN 77, and has been in continuous development since 1978. Dataplot is well-documented, with numerous tutorials for using and extending it. In addiiton, over 30 graphic types are supported, such as histograms, box plots, scatter plots and normal probability plots. This tool is currently available in Unix, Linux, OS X and Windows versions. Dataplot is open source, but is trademarked rather than licensed.</p>