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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.


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. Bundled with Chrome browser by default (see notes).
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 Chrome browser during the install process by using the custom install option. The attempt to install Chrome 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 ThaSniper on 2. November 2008 - 13:53  (9966)


I searched for a solution for a free command-line anti-virus tool but you didn't mentioned anything about it on this site.

I think it is very important. When you can't access your windows, or your computer is so badly infected that you can't do anything, or when even the installed anti-virus is compromised, the only thing you can really try is to boot up your computer from cd or usb-disk or something, get a command-line and run an anti-virus. Or remove the hardrive and scan it in some other computer, but you risk infecting the other computer too. Anyway when you try to remove a virus running the infected windows, while you startup and etc, the virus is working already, damaging further your system.

I have a bootable cd with the mcafee anti-virus. But doesn't work on my case. It hangs. I've been searching on the internet, and f-prot used to have a version, but no longer available. AVG have a command-line but it is not stand-alone, you got to have AVG installed (and eventually already infected) on the system. Avast have a solution, the BART cd, but it is paid. Couldn't find anything else...

Booting a clean alternate system and running a clean command-line anti-virus is a must when you have a virus on your computer. But you don't have any info about this. I suggest you post something about this.

Thank you.

by peter on 2. November 2008 - 14:40  (9968)

It poses a real dilemma for us.
We've thought about suggesting eg. Hiren's Boot CD for "unrecoverable" systems but it's a bit of a minefield.
But can we really advise visitors who have all kinds of levels of ability about this topic?
One of our guiding principles is "First, do no harm".

by Anonymous on 2. November 2008 - 19:40  (9983)

See the Boot CD section. I use AVP or Dr.Web with BCD4W (Antivir plugin is also provided), no need for command-line scanners.

by Anonymous on 3. November 2008 - 16:38  (10019)

Thats why avast updates every 10 hours, so thats 2 times a day, and if you buy pro they can send PUSH updates to your email incase of a malware outbreak and avast will then update, that is why it is good

by Anonymous on 3. November 2008 - 19:14  (10024)
by Anonymous on 4. November 2008 - 4:14  (10038)

After giving both Avast and AntiVir another spin, I decided to stick with AVG since they've seemed to be the most reliable with respect to frequent updates, maintaining its status as 'free as in beer' software and continuous enhancement. I'm turned off by Avast and Avira's requirement that you periodically renew your license which I suspect might be due to their lack of commitment in keeping their wares free forever. Although that could easily be the case with AVG as well, I do appreciate that their free license is 'free forever' with no strings attached. There was that forced upgrade from v7 to 8 which did tick me off a little, but 8 seems to be okay so far - more bloated sure, but still reasonable.

About the Link Scanner, disable it. Select 'custom' when you install the software and go ahead and install the suite without it. It slows down browsing considerably since it proactively scans EVERY link on a page. When you set Google to display 50 search results, you can see how this can get to be a problem. I'm going to keep a close eye on both AntiVir and Avast and will be ready to switch in the future once compelled.

by Anonymous on 4. November 2008 - 20:17  (10058)

No Thanks !

by Anonymous on 5. November 2008 - 6:49  (10070)

Could not agree less with Jonathan T. One security tool monitoring and executing antimeasures in memory is conflicting enough when running regular runs. Two is stupid and simply unnecessary. The right AV tool is smarter and faster (less false positives, conflicting lock ups, and stack heap) than two antimeasures running in memory. The savvy user uses the most basic basic firewall that reports bi traffic, a good AV, and another anti spyware / adware on demand scanner. Nothing else is required (other than the common sense filter) if browsers are set to update and to delete everything at close.

Kevin D. Mitnick
Mitnick Security LLC

by JonathanT on 5. November 2008 - 8:41  (10077)

I don't mean running two antiviruses. I mean running a real-time antivirus and another type of security product, such as a HIPS or a sandbox. Sorry if it was a bit confusing.

by Anonymous on 5. November 2008 - 9:27  (10079)

I find it interesting that a convicted hacker has a computer security company.

by Anonymous on 5. November 2008 - 15:41  (10090)


I've heard ThreatFire is pretty good.

by Anonymous on 6. November 2008 - 4:59  (10113)
by JonathanT on 6. November 2008 - 5:50  (10115)

Threatfire is more of a HIPS program. It's mentioned here:

by Anonymous on 10. November 2008 - 0:11  (10275)

Has anyone tried prevx products? Prevx CSI seems to be their most popular. It uses a community approach to check if you're infected or not. scan only takes a couple of minutes, and they claim to have the largest spyware database, although this could just be advertizing hype. Any experts out there willing to try this program and report your findings? We'd all certainly benefit.

by Anonymous on 12. November 2008 - 13:00  (10391)

I think tha sniper,

what may assist you in your search for a command line scanner is the very secretive "Trendmicro's Sysclean" tool,

you have to get your head round this at 1st but once you do its very easy to setup and use, my advice is to read the "readme.txt" file very carefully.

you need all these files to make it work from there site

File List

o - the main executable module
o readme.txt - this file
o lpt$vpn.XXX - malware pattern file (see Requirements)
o ssapiptn.da5 - spyware pattern file (see Requirements)

you need to go here under the "other" section you will see "Sysclean" tool here

Like I said, read the readme file, its all there what you need to do.
Create a new folder under your drive to be cleaned e.g. root C:\ directory put the sysclean tool and the 2 pattern files in that same folder, make sure you got the latest of everything and the correct pattern files it can be confusing when you see how many they got for different programs.
I would then recommend you reboot into F8 safe mode and run the scanner ticking all the options you want it to perform.

I really like this scanner its simple and effective and really should be all we need these days for a free tool. see what you think ;o)

by Anonymous on 13. November 2008 - 5:15  (10418)

I've been using Antivir for a long time. Unfortunately my installation cannot get through updata. It always tried to download an file over 400M. It's very ridiculous. What's going on?

I ever used COMODO for serveral months, it gave me a good impression.
Now Comodo shipped their Internet Security (including firewall and Antivirus). It's looks very attractive. I searched for news on internet about it. The product got highly appraised( Does anyone have some experience about it?

Do you have any suggestion?

by Anonymous on 13. November 2008 - 10:18  (10429)
by JonathanT on 13. November 2008 - 10:30  (10430)

I personally think the antivirus is too new. A moderator from their own forums have said that they hope Comodo AV to be around the same level as AntiVir, Kaspersky, etc in a year or so.

But according to Comodo is awesome. And Comodo claims they are getting lots of real-world samples with their Comodo Instant Malware Analysis.

by Anonymous on 13. November 2008 - 14:57  (10439)

I doubt that the Tests from AV-comparatives are good either. For me, Kaspersky 5.5 has found much more Viruses / Trojans than NOD32 2.0 & 2.5, Avira AntiVir 6.0 & 7.0 Personal Edition Classic (Free), Avast Home 4.6, AVG Free 7.x, Comodo AntiVirusSpyWare and BitDefender 8 Free, when i changed from Norton 2004 / 2005 to test the mentioned AV programs above. I sticked to Kaspersky 5.5 and 6.0 back then. Kaspersky also had a better performance than NOD32 that day. All Virus programs found about 1 to 5 Trojans more than Norton, except Kaspersky, which found about 20 more. NOD32, AVG, AntiVir and BitDefender had many false positives. Comodo deleted hal.dll, which was easily restored using the windows cd with rescue mode.

In the beginning of 2008 I had one WoW Trojan (this time i had AVG Free 7.5 and AVG 8.0 Beta, which was noticed bei Kaspersky 2009 Beta (both KAV and KIS), where the others (NOD32 3.0, AVG Free 8.0, AntiVir 8 Personal Edition Free, Avast Home 4.8 and BitDefender 10.0 Free failed to detect it. Also ZoneAlarm Free 7.x and Comodo Personal Firewall Pro 2.4 (Free) & Comodo Personal Firewall 3.0 (Free) failed to detect that svchost got hijacked. Also Browser AV-Scanners (BitDefender 8, Kaspersky 7.0, Panda AntiVirus Online Scanner, ESET NOD Online Scanner and Trend Micro House Call (6.5 and 6.6 Beta) failed to find the Trojan.

Don't misunderstood me. These tests are good, but everyone should do their own "test". As for the new test above. I do believe that more Viruses, Trojans & Worms are better for a test than AV-comparatives are using, also because AV-comparatives say that Kaspersky has much false positves.

Especially if i think about sending unknown files to Kaspersky, ESET, Avira, Avast, AVG and BitDefender, I like Kaspersky most. They always reply if the files contain a virus/trojan/worm or not. From all other companies i didn't get a response, except from AntiVir and TrendMicro. Both answered on 1 or two requests from about 30 (which Kaspersky answered everytime). Also the support is great for Kaspersky. When i was using the trial version of Kaspersky Anti-Hacker and got a BSoD I uploaded the memory dump (1GB packed with RAR to 200MB) on their ftp and they fixed it the next day. When i got another BSoD some days later, i uploaded a textfile with the self-analized memory dump using Windows Debugging Tools and they fixed it. They even thanked me for reporting the issue. As for me, I stick with Kaspersky, because of the given reasons above.

by Anonymous on 15. November 2008 - 9:25  (10514)

anitivir ROCKS!!!

by Anonymous on 15. November 2008 - 16:28  (10525)

does anybody know why the umbrella won't open on avira antivir. when i right click it has a check next to antivir guard enable but doesn't open. i don't know if this has been discussed before or not. to many pages to go through to find out. can't find the answer anywhere, hope you guys can help. thank you.

by Anonymous on 15. November 2008 - 19:50  (10529)

Better check the Antivir forum. It's a known problem, I've had it myself, but not recently. Are you using the latest build and definitions ? In my case I've had to unninstall and reinstall when upgrading to release 8.0. There are also known incompatibilities with Windows Defender, if you're using Vista, try disabling it.

by Anonymous on 15. November 2008 - 20:03  (10531)

You might as well want to know how to disable Avira splash screen:

by Anonymous on 15. November 2008 - 20:06  (10532)

CSI is just a scanner, it doesn't remove any malware.

by Anonymous on 15. November 2008 - 21:06  (10535)

everything is updated. using windows xp. have spyware terminator and comodo firewall.

by Anonymous on 15. November 2008 - 23:09  (10537)

Just tried Avast after using Avira for several years. Gizmo's advice to rate Avira so highly for so long swayed me then. After having Avast one week it destroyed my computer. Took it in for servicing an the techs said Avast had detected several false positives that it removed causing several programs and the operating system not to work. I'm out $175.00 over this stupid Avast! The techs said all freeware like this is bad because there is no support after this sort of thing happens. Forget Avira, forget Avast, I'm going to purchase McAfee.

by Anonymous on 16. November 2008 - 0:15  (10539)

"Forget Avira I'm going to purchase McAfee" :D :D :D

by Anonymous on 16. November 2008 - 6:25  (10550)

This one is simple: Bought and paid for antivirus is the best.

by Anupam on 16. November 2008 - 8:00  (10557)

Thats your opinion, but you are so wrong about it. Free ones listed here are not anyway less than the paid ones.

Anupam Shriwatri, India