Many companies offer free versions of their popular antivirus programs for home users while offering versions with more advanced features as an upgrade option for professional and business users.
Important: There are no "on-demand only" (without constant virus protection), trial, or shareware antivirus programs in this list. These are the best antivirus programs that are completely free and work similarly to expensive programs from companies like Norton and McAfee.
Anti-Virus Free from AVG is the best free antivirus software available. AVG Anti-Virus Free is a full-fledged antivirus and antispyware tool, includes an email scanner, link scanner, scheduled scanning options, automatic updates, and more. There is no need to pay for an antivirus program when the best free antivirus software in the world is just a download away.
AVG Anti-Virus Free works on Windows 7, Windows Vista, Windows XP and Windows 2000.
The huge number of premium features, frequency of updating, and install-it-and-forget-it aspect of AVG's Anti-Virus Free really do make it the best of the best free antivirus programs available today.
AVAST Software's avast! Free Antivirus most certainly deserves to be on any list of the best free antivirus programs. avast! Free Antivirus has fully functioning antivirus and antispyware engines protecting your PC from threats from the Internet, your files, emails, and even instant messages.
avast! Free Antivirus supports Windows 7, Windows Vista, Windows XP and Windows 2000.
One big reason I included avast! Free Antivirus as a best free antivirus program is because of its "heuristics engine" which can detect previously unknown viruses and other malware. I also like the fact that AVAST has been making this antivirus product since 1988 and is often cited as the most installed antivirus product.
Tip: During the avast! installation, you're asked to install the free Google Chrome browser. It's not required so if you're not interested just uncheck the box. Also, you are required to register avast! to use it more than 30 days but registration is free and pretty simple. You'll also have to reregister once per year - again, for free.
Security Essentials from Microsoft is definitely one of the best free antivirus programs available right now. Microsoft is relatively new to the antivirus game but don't let that scare you - Security Essentials is a fantastic antivirus program that protects you from all sorts of malware, updates automatically, and is incredibly easy to use.
Microsoft Security Essentials supports Windows 7, Windows Vista and Windows XP.
Two of the biggest reasons I added Microsoft Security Essentials to this list of the best free antivirus software is because it's directly from Microsoft and also because it's very easy to see if you're computer is secure from threats: if the icon next to your clock is green, you're in good; if it's red, something is wrong.
Comodo Antivirus from Comodo Security Solutions is another excellent program, easily one of the best free antivirus options out there. As of this writing, Comodo Antivirus bills itself as the "Best Antivirus on the Market. Guaranteed." due to its proprietary Defense+ technology. Comodo Antivirus also protects you from several threat sources, just as most of the other best free antivirus programs on this list do.
Comodo Antivirus works on Windows 7, Windows Vista and Windows XP.
Comodo Antivirus is easily one of the best free antivirus solutions solely because of its Defense+ technology that, by default, assumes unknown files are threats instead of safe. That sounds like it might cause problems but Comodo Antivirus utilizes some other technologies to make the whole process silent but still very effective.
Avira AntiVir Personal protects you from viruses, Trojans, worms, spyware, adware, and various other kinds of malware, making it a fully functional antimalware tool and certainly one of the best free antivirus programs.
Avira AntiVir Personal works on Windows 7, Windows Vista, Windows XP and Windows 2000. Avira also makes a version of AntiVir Personal for UNIX.
The scope of malware that Avira AntiVir Personal can keep you safe from is alone enough to make it one of the best free antivirus software programs but the heuristics and ease of use add to its value too. The only things I didn't like about Avira AntiVir Personal was the configuration you have to complete after installation which might be difficult if you're a computer novice.
Tip: You're asked to register during the Avira AntiVir Personal installation but it's optional. Just uncheck the box and continue with the install.
Panda Cloud Antivirus protects you from several kinds of malware threats - viruses, worms, Trojans, adware, and more - just like all the other free antivirus programs in this list.
What makes Panda Cloud Antivirus one of the best free antivirus programs is that it does its job from "the cloud" meaning the hard antivirus work that typically slows down a computer is done on computers elsewhere on the Internet, freeing up your computer to work like it should and protecting you from malware even better.
Panda Cloud Antivirus supports Windows 7, Windows Vista and Windows XP.
Tip: Panda Cloud Antivirus tries to install a toolbar and set Yahoo! as your browser's home page during the installation process so uncheck the boxes before continuing if you don't want them. Neither are required to use Panda Cloud Antivirus.
Immunet Protect FREE is a unique, cloud-based antivirus program, much like Panda Cloud Antivirus. Immunet Protect FREE protects your computer from bots, worms, viruses, Trojans, keyloggers, and spyware.
Immunet Protect FREE works on Windows 7, Windows Vista and Windows XP. You must also be connected to the Internet at all times.
I think Protect FREE from Immunet is one of the best free antivirus programs for several reasons: you never have to update it, it has completely free telephone based support, and it can be run alongside some of the other best free antivirus tools like AVG Anti-Virus Free, Microsoft Security Essentials, and avast! Free Antivirus, increasing your overall protection!
digital-defender Antivirus isn't a popular antivirus program but it should be. It's certainly one of the best free antivirus software programs you'll find. It's a full antivirus and antispyware program and updates on a daily basis.
digital-defender Antivirus supports Windows 7, Windows Vista and Windows XP.
The relatively small installation size, daily virus definition updates, and full antispyware features make digital-defender Antivirus one of the better tools in my collection of the best free antivirus programs.
PC Tools AntiVirus Free offers basic protection against viruses and other malware. While not my favorite, AntiVirus Free is still one of the best free antivirus programs you'll find.
PC Tools AntiVirus Free works on Windows 7, Windows Vista and Windows XP.
The biggest problems I have with PC Tools AntiVirus Free are the reminders throughout the program that there's a not-so-free version that you should upgrade to. To be fair, you probably won't notice it since the program runs silently in the background to protect you from viruses. I probably find it annoying because most of the features available in the upgrade are included for free in some of the higher rated best free antivirus programs above.