Mozilla’s Observatory scans for a wide range of web security mechanisms. The tool doesn’t scan for vulnerabilities in the actual website code. Only 121,984 of 1.3 million websites performed with the tool received a passing grade. Some of Mozilla’s own websites were among those that failed the test, including addons.mozilla.org, one of the organization’s most important websites, received an F. The code behind Observatory is open source and an API and command-line tool is available for administrators.”]