What is KWFinder? Well, KWFinder is really an alternative to Google’s keyword planner, which just sucks. Anyone that uses AdWords or any of Google’s tools on a daily basis know that they are just very clunky and the UI is lacking. But of course, it is free so sometimes you can’t be too picky. But in my opinion, if a tool provides real value and speeds up my work, then it is worth every penny.
Of all the tools listed in this article, Moz Link explorer is an old one & quite popular. If you want to compare backlinks between two or more domains, Open Site Explorer is worth trying. This tool works best when you have a paid account of SEOMOZ though a free version of this tool is good enough to get you started checking the backlinks of your site and the sites of your competitors.