This add-on automatically removes all garbage like "utm_source=*" from URLs. These fields are provided for the Google Analytics and they are not a necessity. Example of URL with garbage fields: http://bigpicture.ru/?p=431513&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+bigpictures+%28%D0%9D%D0%9E%D0%92%D0%9E%D0%A1%D0%A2%D0%98+%D0%92+%D0%A4%D0%9E%D0%A2%D0%9E%D0%93%D0%A0%D0%90%D0%A4%D0%98%D0%AF%D0%A5%29 Pure URL: http://bigpicture.ru/?p=431513 By default, Pure URL removes these garbage fields: — utm_source, utm_medium, utm_term, utm_content, utm_campaign (spyware fields for the analytics.google.com) — yclid (spyware fields for the metrika.yandex.ru) — feature (a garbage field on the youtube.com) — fb_action_ids, fb_action_types, fb_ref, fb_source, action_object_map, action_type_map, action_ref_map (spyware fields from the facebook.com) — ref, fref, hc_location (garbage fields on the facebook.com) — ref_ (garbage field on the imdb.com)