To weed out bad links. If you are trying to rank for the keywords you are targeting at Google search engine, backlink checking is a must. By this, you can check and see if there are negative links that (links coming from porn, adult, casino or gambling site) points to your site. If some are found, you can then request the owner of the site to remove it or better yet, make Google discount it (via Google disavow tool found at Google webmasters account).
To see what kind of links your competitors are having. At SEO point of view, checking links that your competitors are having, especially if they are ranking highly than you, can give you an idea or two on what to get for your blog or website to reach the rank you are targeting. Some calls this one competitive intelligence. This is one of the biggest reason why backlink checker tools around are being offer with a hefty price tag.
There are still lots of things to be said why backlink checking is important. But the above reasons can surely make you wanted to check few blogs and their backlinks right now. So without further ado, here are two awesome backlink checkers that you can freely use.
Open Site Explorer by SEOMoz.Org
For me, this one is the best among the free link checkers online. It has a paid option but the free one can kick start your backlink checking campaign in a good way.
For a free tool, ahrefs is surely one of the biggest winners. Why? It gives you great link reports with different kind of details. Aside from the numbers, it also offers reports in graphical presentation which is nice and cool.
Test the tools out and let me know how they helped you and your blog.