This tool shows you what is the status code returned by your server. This HTML Status code is important for resolving the URL Canonicalization. For example
Search Engines will tend to assume that all the above links are different pages and may slap the duplicate content penalty on the given site if they are not properly addressed to point to one single unified URL. So it would be in our - Webmasters - interest to see that we point all but one to the preferred mode of URL through a server side permanent redirection. This tool given below will show you if your redirection status is the preferred 301 (permanently moved) mode of redirection.