gnuplot Gnuplot is a portable command-line driven interactive data and function plotting utility for UNIX, IBM OS/2, MS Windows, DOS, Macintosh, VMS, Atari and many other platforms. The software is copyrighted but freely distributed (i.e., you don't have to pay for it). It was originally intended as to allow scientists and students to visualize mathematical functions and data. It does this job pretty well, but has grown to support many non-interactive uses, including web scripting and integration as a plotting engine for third-party applications like Octave.
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Graphviz, A Graph Visualization Software
Grappa, A Java Graph Package
Orange Orange is a component-based data mining software. It includes a range of preprocessing, modelling and data exploration techniques. It is based on C++ components, that are accessed either directly (not very common), through Python scripts (easier and better), or through GUI objects called Orange Widgets.
Sodipodi Sodipodi is a vector-based drawing program, like CorelDraw® or Adobe Illustrator® from the proprietary software world, and Sketch or Karbon14 from the free software world. It is free software, distributed under the terms of the Gnu General Public License, Version 2.
Sodipodi uses W3C SVG as its native file format. It is therefore a very useful tool for web designers.
It has a relatively modern display engine, giving you finely antialiased display, alpha transparencies, vector fonts and so on. Sodipodi is written in C, using the Gtk+ toolkit and optionally some Gnome or KDE libraries.
Sodipodi works under most versions of Unix and Windows.
Inkscape inkscape is an Open Source vector graphics editor, with capabilities similar to Illustrator, Freehand, CorelDraw, or Xara X using the W3C standard Scalable Vector Graphics (SVG) file format. Supported SVG features include shapes, paths, text, markers, clones, alpha blending, transforms, gradients, patterns, and grouping. Inkscape also supports Creative Commons meta-data, node editing, layers, complex path operations, bitmap tracing, text-on-path, flowed text, direct XML editing, and more. It imports formats such as JPEG, PNG, TIFF, and others and exports PNG as well as multiple vector-based formats.