The Hyves API allows you to use usernames to retrieve a user. It should be noted that usernames should not be used for anything else. Unlike most websites, Hyves allows users to change their usernames; and they do so regularly. So it would be an especially bad idea to use usernames as primary key for anything; the user with username "john" today, may not be the same as the user with the username "john" tomorrow.

On the Hyves website, the username is not displayed anywhere, except in the URL for the personal overview page. That is why there is no API function to retrieve the username for a user. Although the username can at the moment be deducted from the "url" field of a user, the format of that link may change without notice.