We present here an open source software package called UsimagTool which consist of a set of algorithms and a graphic user interface (GUI) specially designed for research purposes in Ultrasound image processing. This tool is based on the C++ open source libraries ITK, VTK and FLTK. One of its main features is its modular and flexible architecture, which allow developers to modify or include image processing algorithms very fast. UsimagTool includes several algorithms developed specifically for Ultrasound data processing, that has been coded using the ITK and VTK convention. The algorithms included and described here are new implementations and they are not part of the official ITK or VTK releases. They are three filters (anisotropic Wiener, Speckle Reduction Anisotropic Diffusion, and Tensor guided Anisotropic Diffusion) one segmentation algorithm based on a Markov random field model, and a demons registration suitable for US data. There is also a user friendly GUI designed for segmentation and registration tasks, with three independent viewers to display simultaneously three different data sets. The GUI can be easily adapted or modified with little effort for other tasks, for instance it can be redesigned for clinical use.