High Quality Content by WIKIPEDIA articles! Protovis is a visualization toolkit for JavaScript that takes a graphical approach to data visualization by allowing the user to specify how the data should be encoded in the marks representing it on the screen. The project is led by Mike Bostock and Jeff Heer of the Stanford Visualization Group, with help from Vadim Ogievetsky. Protovis uses SVG image for rendering, allowing visualizations to be seamlessly inserted into pages.