NAViGaTOR is freely-downloadable to academic users from the downloads section of the website available at: http://ophid.utoronto.ca/navigator/downloads.html. The application can be installed and run on Microsoft Windows, Linux / UNIX, and Mac OS systems. Users can load networks from a tab-delimited file (e.g. NAViGaTOR XML, BioPAX or PSI formats), or can be generated dynamically by executing a visual query to the Interologous Interaction Database (I2D), an online database of known, HTP, and predicted protein-protein interactions for human, rat, mouse, fly, worm, and yeast or cPath. The website also provides tutorials for users in HTML or Flash format to help with navigating the software.