This web part makes adding canonical links to pages a lot more straight forward. It is full of features that others don't have, including href lang and wildcard support.
Href lang support - multiple languages based upon kentico multi-language configuration (sub-domain, folder bases, query string based).
URLs are correctly modified based on kentico SEO settings.
Support for wildcard / dynamic urls.
Points back to the original document for linked pages.
Allows control of the querystring behavior.