If your computer is already infected with malware, see our related topic Remove Malware for Free .
In early days, the Windows OS did not include antivirus software. That omission gave rise to the antivirus software industry.
Eventually, Microsoft introduced a free software option. Microsoft Security Essentials was introduced in 2009 as standalone malware protection for Windows XP, Vista and 7. (Steve of Fixer-1 participated in the early validation testing of Security Essentials and was recognized by Microsoft for those efforts.) Security Essentials was integrated into Windows 8, 8.1 and 10 as Windows Defender and rebranded as Microsoft Defender Antivirus in 2020.
Microsoft Defender is now built-in to Microsoft Windows 11. Therefore, it is open to debate whether it is necessary to utilize third-party antivirus software.
If you are interested in supplementing Windows’ built-in antivirus protection, read on. If you opt to install a third-party antivirus product, the built-in Windows antivirus will turn itself off to avoid slowing down the computer by running two such programs at once.
There are several antivirus vendors that offer excellent free versions of their products for computers running Microsoft Windows. While you may assume the paid versions offer vastly better protection, that is not typically the case. The paid versions always offer some additional features, but the antivirus protection is usually very similar.
You can assess the effectiveness of free and paid antivirus software products by reviewing the test reports at AV-Test.org. Often the exact free editions are tested but sometimes only the comparable paid versions are tested. These products also include antispyware protection.
When installing any free software, be alert to uncheck the boxes for browser toolbars or other included add-ons that may add more clutter than value.
Antivirus and security software products typically undergo significant design changes at least every 1-3 years. As a result, the top rated titles are reevaluated every 60 days at AV-Test.org and may be re-ranked accordingly. The top rated product this year may not be top-rated next year. Therefore, the objective of using the ‘best’ antivirus product is a moving target.
Free Windows antivirus products tested at AV-Test Institute:
- Get Webroot Secure Anywhere for free when you open a free Ally.com checking account.
- Avast Free Antivirus
- Windows 10 Built-In Security – Includes Windows Defender AntiVirus software.
- Panda Cloud Antivirus Free Edition – Click the Options button during installation to avoid installing the additional browser toolbar.
- Your Internet Service Provider (ISP) may also offer a free version of a typically non-free antivirus software.
No free or paid product can provide 100% protection from malicious software.
When downloading a free version make sure you select the proper download button so you don’t end up with a 30-day trial instead. Do not select a ‘trial’ version if you intend to download a free version.
These products all have online support forums where you can get answers if you need help installing the software. Uninstall your old antivirus product first.
Sometimes you may need to download one of these uninstall tools for your current antivirus in order to install any free (or different) version.
So why do these companies offer free versions? Because they hope you will eventually upgrade to a paid version. And they sometimes include advertising add-ons they get paid for like switching your default search provider to Yahoo or Google or installing an additional browser toolbar unless you uncheck these options during installation.
Antivirus product reviews and ratings websites:
PC Magazine – Various antivirus product reviews by editor Neil Rubenking. Neil publishes updated reviews and security news during the year.
AV-Test – New ratings summary posted every 2-3 months. Click on a product line item for a further details on how that product was rated.