They are just advertisement schemes and do not offer any competitive detection, cleaning or prevention capabilities. You should definitely avoid free antivirus software because as soon as you install them they will tell you that you should upgrade to the full version to get real security. What to do when a website says you have malicious software on Mac? If you are browsing a website and it claims to have detected malicious software, malware, or a virus or simply states it has 'detected problems' with your Mac, then follow these steps.
