Visiting https://getfiddler.com should not result in a error like

Your connection is not private

Attackers might be trying to steal your information from getfiddler.com (for example, passwords, messages or credit cards). Learn more

NET::ERR_CERT_COMMON_NAME_INVALID
This server could not prove that it is getfiddler.com; its security certificate is from www.fiddler2.com. This may be caused by a misconfiguration or an attacker intercepting your connection.