Unfortunately, I have to advise against using this tools as it has been very inaccurate in my experience. It frequently shows registered domains as available. Once, I was doing a quick search of the "top 500" keywords, and it showed golf.info, games.info, and several others as available. Excitedly, I go to my registrar and do a search for those domains. Quickly, my high hopes are dashed as my registrar showed those domains as actually not available.