Html Validator for Firefox and MozillaINSTALLATION (Firefox Version >=57 or Chrome) Production version:The webextension is available for Firefox (Version>=57) and Chrome: Development version: You have to download and install the latest version of the extension that is available in GitHub (https://github.com/mgueury/html_validator/). See instruction here. PREVIOUS VERSION (Firefox Version <=56) You have to download the extension 0.974
