We must, at first, mention the existence of a French tool which is not a portal, the Dictionary of active English authors from 1300 to 1600 (Dictionnaire des auteurs anglais actifs de 1300 à 1600 of Jean-Philippe Genet, online on the site of the Laboratoire de Médiévistique Occidentale de Paris (LAMOP). This dictionary is, indeed, a database, and gives many elements on the life and manuscripts of these authors, as well as bibliographies.
Note : All medieval English authors are not mentionned here, only those who are really present on the web or who have a various production.