Quantitative susceptibility mapping (QSM) and susceptibility tensor imaging (STI) are two recently developed imaging methods for quantifying tissue’s magnetic property. Magnetic susceptibility offers a new contrast for high-resolution anatomical imaging; it further provides important information on tissue’s chemical composition, especially myelin and iron, and white matter microstructures of the brain. However, processing QSM and STI still requires advanced technical expertise. The growing application and wider acceptance of this new technique has generated a need for a comprehensive software package that can easily perform all these analysis. Here, we have developed such a tool named “STI Suite”. This software is based on our previous works. In this Matlab-based software package, we have implemented the essential algorithms for phase processing, QSM, STI, and related analysis tools. To facilitate the dissemination and evaluation of these methods, we make STI Suite freely available at http://people.duke.edu/~cl160/ for non-commercial academic use. STI Suite contains both Matlab command-line functions and graphical user interfaces (GUIs) for phase processing, QSM, STI, and related visualization and ROI analysis tools.