This plugin helps you to keep the link juice by redirecting all non-existing URLs (they return error 404) to the blog front page using 301 redirect.
As you probably know, incoming links play important role in ranking well in Google and other search engines. Therefore you should assure that every incoming link leads to one of pages on your blog. This may be a challenge, because World Wide Web is dynamic and changes every day:
All of the above leads to link juice waste. You can avoid this by using this plugin. It redirects all non-existing URLs which normally return a 404 error to the blog front page using 301 (permanent) redirect. This way everyone who comes to your blog via broken link (both people and robots) will be redirected to the front page.
The only one exception are files in root blog directory with names starting with noexist_. They are used by Google to verify page in Google Webmasters Tools, so Link Juice Keeper does not redirect them.