Best Free Antivirus Software

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Antivirus software provides an essential layer of protection from viruses, trojans, worms, spyware, adware, dialers, keyloggers, and rootkits. Don't let the name antivirus confuse you. These days every good antivirus has good detection rates for all forms of malware, not just viruses. The term malware includes viruses, trojans, worms, spyware, adware, dialers, keyloggers, rootkits, and any other software which performs malicious activities on a computer.


Sadly, the amount of malware currently in circulation is so large that no antivirus could possibly detect all of it. Despite vendor's claims, no single antivirus solution can detect nearly all new malware. There are some products out there, including some in this review, which include technologies which are able to adequately protect a computer, but any product which relies mainly on detection is statistically doomed to fail at some time. Also, using more than one real-time antivirus at the same time uses much more system resources, can cause system errors, and can even reduce protection. For my advice on how to compensate for these weakness of antivirus products, to a large extent, please see my other article about How to Stay Safe While Online. Having a good antivirus product does go a large way towards adequately protecting your computer, but in this day I would highly recommend that you add additional layers to your security.


Below I have reviewed some of the most effective Free Antivirus products currently on the market. In order to make this review more unbiased, although of course my own intuition and experience does affect my judgment as well, I came up with a particular methodology for comparing these products. This methodology is described in the following section.

Methodology For Comparing Products

The main motivation behind why I came up with this particular methodology for this review is that I value system protection against real world threats above all other categories by which an antivirus is commonly judged. It does not matter to me whether an antivirus protects the user by detecting malware, blocking dangerous sites, behavioral analysis, sandboxing, or any other approach. The most important thing is that at the end of the day your system is safe from infection. Thus, that is the attitude I have taken towards reviewing these products.


Therefore, I found Antivirus testing organizations which claim to test products against situations which resemble real-world situations. I narrowed these down by further requiring that the organizations have a relatively long record of producing good, seemingly unbiased, results. The organizations I ended up with, and therefore used for this review, are:



Dennis Technology Labs

From here I looked at all tests ranging to the beginning of 2013. However, if there were more than three tests within that range I used only the most recent three. Also, if given the choice between results from different operating systems, I chose that for the most popular operating system. At the moment Windows 7 is the most popular operating system.

Also, I only considered results if it was specifically the Free Version which was tested. This is because the results for the Paid Version of the products in this review, with the exception of Comodo Antivirus, are often quite different from those for the Free versions.

In addition, I did not count it against any of the products if they were not tested by multiple organizations. As long as they were tested by at least one, within the above-mentioned period, they were considered. This criteria was chosen because there are many reasons to choose not to participate in a test. Thus, it should not be held against the product if they were not tested by multiple agencies. However, if they were not tested by any, this makes it impossible to compare them in an unbiased fashion.


Once this data was collected, I then looked at the overall results for the Free Antivirus products discussed in this review, and ordered them mainly according to the quantitative results. However, my own knowledge of the products, and the reviews and experiences of others, were also considered. The results are presented and discussed below.

Discussion And Comparison

Comodo Antivirus is my top pick for advanced users or for Intermediate users who are okay with an antivirus software which will occasionally ask them for input. However, if you do not fall into those categories, or for any other reason find it to not be a good fit for you, then you will likely find my next pick suitable. Also, for those who prefer a complete solution, there is always Comodo Internet Security, which is also free and includes a firewall in addition to all other components which already come with Comodo Antivirus.

The reason I made this my top pick for advanced users or users who are okay with a somewhat talkative antivirus software, is because it is the only product which I feel confident saying that it will protect you against nearly 100% of real-world threats. I have a lot of experience with this product. I am a volunteer moderator on the Comodo forums and have been using it for a long time. I know this product very well, and am entirely confident in its ability to protect.

Comodo Antivirus uses the cloud to facilitate the detection of the most recent malware, as do many other Free Antiviruses reviewed in this article. However, Comodo also incorporates a Behavioral Blocker, which will automatically sandbox all software which it does not know for sure is safe. Thus, the user is protected from nearly all malware, which will either be detected by the antivirus component or sandboxed by the Behavioral Blocker. It will also analyze unknown applications for suspicious behavior, and alert the user accordingly.

However, as mentioned previously, users who do not want a somewhat talkative antivirus should continue to my next pick. Also, by default Comodo Antivirus has small advertisements (which can be disabled as shown here). Also, during installation users should be sure to click the Customize Installer option, which is near the bottom-left of the installation window. This will allow them to uncheck additional software, which the installer will automatically install with Comodo Antivirus unless unchecked. This software is not dangerous and includes a browser, and ad-blocking addon, and an optional paid service which would allow Comodo technicians to assist you with any computer problems you have. These, and a later option to change your homepage to support Comodo, can safely be unchecked during installation. Even with this extra hassle, this software is still my top pick, but I do wish they made the process simpler.


Avast! Free AntivirusAvast! Free Antivirus is has very good protection rates. Avast has many different protection shields, boot-time scanning, a behavioral blocker, an internet site ratings plugin, script malware protection, and access to cloud-based protection. It's arguable whether their ratings plugin offers comparable levels to WOT, but the script malware protection can prevent certain browser exploits, a feature not available in any of the other free AV's reviewed.

Avast is also relatively light on resources. However, do note that Avast requires a free registration to function after 30 days, and the default installation installs the Chrome browser unless you uncheck it. Also, note that the OpenCandy advertising component is integrated into the Software Updater tool in Avast. More information about OpenCandy can be read here. Thus, if a user selects this option during the install they will end up with OpenCandy on their computer. Please be very careful about this option if you choose to install 


Panda Cloud AntivirusPanda Cloud Antivirus is another excellent choice for average users, who may find both Comodo Antivirus and Avast too confusing. It has a simple interface, completely automated features, access to cloud-based protection, and has been shown to be very good at protecting a computer. Panda Cloud Antivirus has a behavioral blocker, web protection, and access to cloud-based protection, all of which will help increase your security.


AVG Anti-Virus Free EditionAVG Anti-Virus Free Edition is also a decent choice for average users. My analysis of the results, as discussed in the methodology section, does show that it does a decent job of protecting your computer. However, it appears that the above Antivirus products tend to do better. Also, it comes with advertisements (but they can be disabled).


Avira AntiVir Personal EditionAvira AntiVir Personal Edition is another product which has a very good reputation. However, the free version was not tested by any of the three testing organizations I referenced in my methodology. Therefore, I cannot currently recommend it above any of the previously mentioned products.

However, other comparative tests do show that it has very high detection rates for malware. Also, many users have used it and found that it is very effective. Also, users have access to cloud-based protection. AntiVir is certainly a good choice for a free antivirus, but due to the lack of real-world testing, at this time I cannot recommend it above the other products in this review. Hopefully in the future they will have the free version tested by these organizations as well.


Bitdefender Antivirus Free Edition

Bitdefender Antivirus Free Edition is another free antivirus product which has a very good reputation. However, the free version was not tested by any of the three testing organizations I referenced in my methodology. Therefore, I cannot recommend it above any of the previously mentioned products.

The engine for this product appears to be the same as for the commercial product. However, the level of protection provided has not been shown identical with the paid version, which is why I did not use the results for the paid version in my analysis. The user interface for this product is very minimalist. Thus, it may be attractive for novice users, though more advanced users may be frustrated at the lack of customization. Bitdefender Antivirus Free Edition is a good choice for a free antivirus, but due to the lack of real-world testing, at this time I cannot recommend it above the other products in this review. Hopefully in the future they will have the free version tested by these organizations as well.


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Quick Selection Guide

Comodo Antivirus
Gizmo's Freeware award as the best product in its class!

Runs as a stand-alone program on a user's computer
This has full real-time protection capability, including real-time antivirus, behavioral blocking features, cloud-based protection, and an automatic sandboxing function which protects users from nearly all malware.
The automatic sandboxing function, although not very intrusive, may be too talkative for some users. Also, by default non-intrusive advertising is enabled (although it can easily be turned off).
Version 6.x
32 and 64 bit versions available
Unrestricted freeware
There is no portable version of this product available.
Windows XP, Windows Vista, Windows 7, Windows 8.x

Take care to avoid the installation of unwanted software during installation. To do this use the customized installer button, which is on the lower left-corner of the screen during installation. Additional software, including a browser, an ad-blocking addon, and an option paid service which would allow Comodo technicians to help you with computer problems, are all included by default.

Avast! Free Antivirus
Runs as a stand-alone program on a user's computer
This has full real-time capabilities, behavioral blocking features, script malware protection, and a low rate of false positives.
Default settings require certain user interaction. It is bundled with Chrome browser by default, and if not carefully avoided during installation the user may accidentally install OpenCandy (see discussion for clarification).
Version 9.x
32 bit but 64 bit compatible
Feature limited freeware
There is no portable version of this product available.
Windows 2000, Windows XP, Windows Vista, Windows 7, Windows 8.x, Mac OS

Take care to avoid the default inclusion of the Chrome browser and OpenCandy during the install process by using the custom install option. The attempt to install these will also be repeated at the program update if the automatic option is chosen.
Quick Start Guide:

Panda Cloud Antivirus
Combines a web service with a stand-alone program
High detection rate of malware, web protection, some behavioural blocker features
Detection rates of real-world malware is slightly lower
Version 2.x
32 and 64 bit versions available
Free for private use only
There is no portable version of this product available.
Windows XP, Windows Vista, Windows 7, Windows 8.x
AVG Anti-Virus Free
Runs as a stand-alone program on a user's computer
Behavioural blocker
Slightly lower signature detection rates
Version 2013.x
32 and 64 bit versions available
Free for private use only
There is no portable version of this product available.
Windows 2000, Windows XP, Windows Vista, Windows 7, Windows 8.x

Forum for support

Avira AntiVir Personal Edition
Runs as a stand-alone program on a user's computer
Outstanding detection of malware
Not the most user friendly
Version 14.x
32 bit but 64 bit compatible
Free for private use only
There is no portable version of this product available.
Windows 2000, Windows XP, Windows Vista, Windows 7, Windows 8.x
Bitdefender Antivirus Free Edition
Runs as a stand-alone program on a user's computer
High detection rates, very user friendly
Lack of customization
Version 1.x
32 bit but 64 bit compatible
Free for private or educational use only
There is no portable version of this product available.
Windows 2000, Windows XP, Windows Vista, Windows 7, Windows 8.x


This software category is maintained by volunteer editor Chiron. Registered members can contact the editor with any comments or questions they might have by clicking here.


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by Anonymous on 26. November 2008 - 3:07  (11025)

Things can (and do) change quite fast in the world of security.
Avast is no longer the solution it once was, and there are far too many problems with AVG8.
Because it does one thing very well, Avira is the way to go !
Until of course, something better comes along !

by Anonymous on 26. November 2008 - 6:53  (11034)

Test Jon, then research the Intertubes, and finally, listen to your posters. One day you may be rewarded for that work. Nice to hear from you Peter.

Dr. Jeffrey Brown
IT Security Specialist

by fat_man74 on 26. November 2008 - 6:59  (11035)

thanks a lot for the reply davy. Yeah that suite was draining me badly, but I've since ditched it for my current protection that was listed. I'm kinda sure there is infection due to the slowness of my computer, but it could just be the resources. I'll definitely consider the gig upgrade on my RAM..there's so much information here and I know experienced people can lead me to the best way possible to secure this system. I think i'm looking for a layered suite that's ideal for this computer.

by Anonymous on 26. November 2008 - 7:01  (11036)

And 2 more meg's of RAM for that load.

by Anonymous on 26. November 2008 - 7:08  (11038)

I recently installed Comodo Internet Security in a computer that had no internet connection trying to install only the firewall, which I've used for a long time as it is a great product. So I find out about the new internet security suite and decide to give it a full go, since you can opt to leave out the antivirus installation. It has worked well so far, running side by side with AVG8. I know about the issues of having two AV, but the computer was clean so no problems have surfaced by having the two AV running together. The only thing that bothers me about Comodo Antivirus (besides the fact that it has a bad detection rate), is that in the five minutes playing with it while configuring the firewall I realized that by default it won't scan any files larger than 20Mb, both the realtime access and on demand. It's major flaw IMHO. You can however change this in the on demand scan but up to 99MB, so it still won´t scan files larger than that. Please, correct me/repost if I'm wrong. Anyway, like I said, didn't play long enough with it.... just to setup the firewall.

by JonathanT on 26. November 2008 - 10:26  (11044)

For testing, wouldn't relying on testing organisations like av-comparatives and av-test be better?

by Anonymous on 26. November 2008 - 18:01  (11068)

Yeah, I have noticed that as well, I think I will post that on the comodo forums, but I think their thoughts on that is probably cause of the real time scanner (aka Defence+) but I will try to find that out.


by Anonymous on 26. November 2008 - 18:17  (11069)

You have alot of software installed, now if your running slow you might want to make sure that not everything is running in the back ground, even alot of smaller programs running can slow you down. Especially with Dell and HP you get alot of programs that run in the background by default and most of them are practically useless or crippled in some way or another. You could run PC Decrapifier to clean up some of that stuff, but then you might also want a start up manager to stop a few of the processes from running (ie the dell update services). And most of the protection software you have listed can be run on demand instead of having them running in the background or in the toolbar like SAS, MBAM, SpywareBlaster CCleaner and Comodo Registry Cleaner. So make sure that those don't start up when you start up your computer cause those are all on demand programs without any real time protection. Although, I might be mistaken with SpywareBlaster. As for MRU-Blaster, EULAnalyzer and TCPOptomizer I'm unfamiliar with them so I'm not sure if they should be running, hopefully someone else can help with that.


by Anonymous on 26. November 2008 - 19:19  (11074)

Dr. Jeffrey Brown has shares in Avira.

Avast scores very highly in all independant tests, so your comment that it is third rate is laughable.

Yours faithfully,

Dr. Phil McAvity

by Anonymous on 26. November 2008 - 19:20  (11075)

Oh yeah, Comodo is stating that BOClean is going to eventually become a part of CIS as well.

by Anonymous on 26. November 2008 - 19:38  (11077)

Ok here is the replys from the comodo forums.

by Anonymous on 26. November 2008 - 19:47  (11078)

Brass tacks here Jon.. Comparitives are faulty most of the time for several reasons. They only test specific detection rates but do not decompile the heuristics to report how or why a product passes or fails a test. There are many things comparitives do not and cannot measure including but not limited to repair success. Comparitives are dated and so are the test subjects. The products are usually several versions old and most comparitive tests are at least 6 months in between. There are several other problems with comparitives I don't have time to discuss in full here. To do this right Jon, you must consider your must have's, and would be nice's.

Must have's:

Security background with education and credentials.

Industry liaisons, designers, compilers, decompilers, even a visit to a product forum to ask a question of their product or their competitors, and even "Hey how bout a beer and some talk, and not ruling out professors here too.

Would be nice's: (but almost a must have)

Resources and staff with live source code to test your products and methodologies.

Again Jon, I don't work here anymore so I can't advise you other to say consult with Ian. You might delete the offending post "pretending to suggest tools for use to another poster in this forum." I made no such comments.

Thank you,

Jeffrey Brown
IT Security Specialist

by Anonymous on 26. November 2008 - 20:30  (11082)

Dr. Phil McAvity,

I have shares in many things. You might read on in this forum and others like it about the ongoing Avast issues that remain unsolved by Alwil. I've clients that ask "does Avast send me false positive code in updates?" I'll simply refer to another Dr. Phil on this site called Alien IP that Avast can't even scan nor ignore without flashing lights and sirens (That's a feature I won't even indulge you in Dr. that this product has that scares the shit out of most first time users).

Please Dr. download and try Avast on Alien IP and watch as Avast destroys Alien IP. It's only one example of this poor performer, but many other Avast users are destroying their safe programs because Avast says to. For now I'll take you at your word your actually a Dr. and have the certs in this field, otherwise I'll just refer you on to this:

Dr. Jeffrey Brown in IT and CS (since we're all hanging it out)
IT Security Specialist

by Anonymous on 26. November 2008 - 22:38  (11088)

Dr. Jeffrey Brown,

You post a link where someone notices a false positive and the Alwil team responds and fixes it within hours.

Yes very third rate that isn't it!


Dr. Phil McAvity in IT and Gynaecology

by JonathanT on 27. November 2008 - 0:01  (11089)

Thanks for the information!

by Anonymous on 27. November 2008 - 0:27  (11091)

I am using avast along with lot of my friends and I never felt a need to go for some thing else.This is one among my essential handpicked softwares.

by JonathanT on 27. November 2008 - 5:23  (11108)

I believe it's still being decided.

by Anonymous on 27. November 2008 - 5:30  (11109)

Hope it helps.

JB :)

by Anonymous on 27. November 2008 - 5:45  (11111)

A pragmatic user surfaces in here!


by Anonymous on 27. November 2008 - 8:11  (11116)


Like most liberals you skirted my invite to test Avast against a safe program on this site called Alien IP and like most lib weenies you shot your load before bringing any truth to the discussion. I doubt you have a PHD in IT since your a medical doctor as well. I think it's safe to say you do not know what you're talking about here since you also have not quoted Avast as having one of the highest FP rates in all of AV history. I think we've now separated the wheat from the chafe here.

IT bla, bla, bla and tons of shingles I'm sure you have too.

Ian, you once had a kind and meaningful site when you ran it yourself. It seems now this has all changed and is outside your reach to correct, so I bid you, your guests here, and Jon a final ado. Please find your own AV answers and solutions to "believe in." I don't get paid to put up with this crap on any site.

by fat_man74 on 27. November 2008 - 23:46  (11129)

Thanks Duskao, I really appreciate the reply and advice....I think it goes hand-in-hand with what Davy advised as far as memory, too. I'll definitely do what you proposed and see what it does for my system. What's your suggestion for extra removal power for spyware, adware, trojans, ect.? Should I just stick with what I have or add some other software?? Also, have suggestions for a layered suite (best possible for my system)...I'd really appreciated it greatly!!!

Thanx a billion,

God Bless!

by Anonymous on 28. November 2008 - 9:43  (11141)

Honestly, I'm no expert by any means, but I would consider myself a computer enthusiast, and most of my experience is from trial and error. Thats just an FYI. But I don't think you really need to change anything, by the sounds of it you have everything covered. As far a layered suites... most of the free ones kinda stink at the moment or have alot of extra stuff in them that isn't needed (adware), so what you have is probably better for the time being. As for your removal power for the spyware, adware and such, you already have two fo the best programs out there for it. SAS and MBAM. Now the best thing you can do is surf with care and regular maintenance of your comp ie. defragging, uninstalling unused programs (unless they are important) and cleaning up unused files and duplicated files (most of which is done with decent cleanup software. Oh, and don't forget to defrag your registries, and make sure not to go overboard with cleaning up registries and always set a system restore before doing anything with registries or you could cause more problems then it's worth. Oh, and since you have fairly low RAM for now-a-days you might want to run a program called "CleanMem" I found it here on this site a little while ago and it runs so that you don't even know it's there, completly unintrusive, and seems to do a better job at optimizing memory then any of the others I have tried. It seems to reallocate the ram leaked by the operating system instead of trying to free up ram that is being used by programs, but that is purly theory on my part, none the less it seems to work. Alright, it's late and I'm sure I'm rambling like I often do so I bid you fare well and good luck.


by Anonymous on 28. November 2008 - 9:55  (11142)

Oh, however, if you really want to try a "suite" that seems to have almost everying, this is something that I'm evaluating right now. Comodo Internet Security (CIS). But I must warn you, it does use the Comodo AV scanner which is only sub-par, however it seems to be quite lite on system resources (generally about 5000K while idle, 10000-20000 while scanning) on my PC and is very fast scanning (on my PC). But if you do decide to give it a try make sure to do a few on demand scans (Kaspersky, BitDefencer, Trend Micro ect)fairly regularly just to make sure that something isn't/hasn't slipped by. But if not you are probably as protected as you can be without being overly paranoid and crippeling you system with malware protetion. Once again.... G'Night!


by korbenPL on 28. November 2008 - 12:09  (11155)

Avira AntiVir Personal Edition with silent updates turned on and splash screen turned off - almost ideal software.

by Anonymous on 28. November 2008 - 21:35  (11176)

Yep, I agree, tweaking Antivir like that makes it a sort of unnoficial upgrade. Better than free & shareware versions.

by Anonymous on 28. November 2008 - 21:47  (11179)

Well bye bye then Dr, don't let Avast scan you on the way out!

by Anonymous on 29. November 2008 - 9:04  (11190)

Just an aside comment about avg.

A curious problem I had with avg (a couple of years ago now). Was reinstalling (at that time) windows 2k, installed OS, drivers , . . , rebooting as requested, then avg antivirus, reboot - windows wouldn't start. Couldn't do a thing, tried repair ect, could boot safe mode but couldn't find problem. Gave up, started again, same place, same result.

Tried the original windows cd (not slipstreamed with SP 4), all OK, even after avg. Download SP4, still OK. Went to disable WFP (patched sfc.dll); A-HA: windows would not boot.

Anyway, fixed the problem; not by putting WFP back, but by tossing avg and going with avast. (Earlier avg versions worked, started about I think v7.??)

Shame avg is broken, now used to avast so wouldn't go back without good reason.

by Anonymous on 29. November 2008 - 15:08  (11197)

I think AVIRA is the best!!! Because it very light and fast. It doesn't slow the PC.

by Anonymous on 30. November 2008 - 22:05  (11242)

My XP Pro SP2 has never had this problem, Or my Vista SP 0, or my XP Home SP2, or my other XP PRO SP2,
Also, that sounds like explorer.exe isn't loading after avast has been installed

by Anonymous on 30. November 2008 - 22:10  (11246)

hmm, when I last checked what people and testing companies say about avast's detection rate, I saw 95%, also avast comes with a web shield and free support, the only software I've noticed that have a web shield were Kaspersky and Avast, I just use avast on every computer because it works perfectly

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