Optical Burst Switching (OBS) is the future of optical internet which provides a promising architecture to efficiently utilize WDM and to fulfill today’s Internet traffic demands. Since this area is yet to mature there is a darn need to study its various protocols. Network simulator is an important tool for researchers and academicians to simulate and model the actual network at a reduced cost compared to the real test-bed experimentation. In this paper various OBS simulators are comparatively surveyed, while highlighting their merits and demerits.