Dimensional Synthesis is of crucial importance in robotics for trajectory planning, task specication in Mechanism Synthesis,CNC tool path planning as well as in micro and nano systems, where kinematics plays an important role. This thesis presents an interactive software for the dimensional synthesis of planar parallel manipulators (PPMs) and spherical four bar motion approximation from a given set of displacements. For PPMs, a user friendly and interactive graphical software has been developed for the synthesis using C++,OpenGL and Qt. The software is designed and implemented using an Object Oriented Programming (OOP) architecture. This architecture naturally maps mathematical formulation of the constraints of PPMs to the OOP paradigm and enables extending the software to handle other types of linkages as well. Using the kinematic mapping approach, the mechanism design problem is transformed into a problem of manipulation of surfaces to visually contain the image curve by simple geometric manipulation of the size, orientation,and location of the constraint surfaces which are developed for all the cases and that yields the desired mechanism. For Spherical Four Bar, a web based software using Mathematica has been developed. The software nds a spherical 4-bar mechanism that best guides through the set of given displacements. It implements an ecient linear algorithm that naturally extracts the geometric constraints of a motion and leads directly to a mechanism for motion generation. The entire process for both the softwares is intuitive and lends designers an understanding of the mechanism design methodology.