This is an effective marketing perhaps because users are buying it in the process.
Some offers free online antivirus then suggest paying for the installation fee later on to offer data security and protection as well. This is usually part of their marketing strategy to attract more customers because most people today are using the online resources. Most antivirus companies are into trend of offering online scanning for their clients. However, online scanning tools also have its pros and cons. You don’t need to be technical expert in order to use this because a few clicks from the interface with already scan your system at no extra cost. It uses simple and friendly user interface as well. Most users would rather use it because it is updated always as signature databases of antivirus tools.
There are a lot of free Mac virus scan online services all over the world today.