MBSVT is a library for the kinematic and dynamic simulation of multibody systems, with direct and adjoint sensitivity analysis capabilities. The MBSVT software was developed in Fortran 2003 language as a collection of Fortran modules and it was checked in several different compilers and platforms. The library can solve the kinematics, forward dynamics, sensitivity analysis and optimization of multibody systems. The distribution includes a Cmake list, gfortran make files, MSV2010 project files, and a collection of training problems. The documentation for the library is available in html and pdf as a reference manual.