If you think this user is violating Mozilla's Add-on Policies, please report this user to Mozilla.
Please don't use this form to report bugs or contact this user; your report will only be sent to Mozilla and not to this user.
HTML Validator is a Mozilla extension that adds HTML validation inside Firefox, Mozilla. The number of errors of a HTML page is seen on the form of an icon
For Firefox 56, use 0.974 (see all versions below).
For Firefox 57, see Web Extensions.