When you manage a website you spend time and money finding links on internet and writing content related to them.
Internet evolve though, the websites that you linked may not have anymore the same content or may be completely offline, this force you to constantly review your links to guarantee your website quality and SEO score.
URL Freezer tracks and checks all the links on your website for you, detect if they change or go offline automatically activating a redirect to a snapshot of the original content.