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.
Also, note that although the download page linked to above does not list Windows XP as being supported, Windows XP x32 is fully supported, although Windows XP x64 has significant limitations.

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 Chiron on 14. June 2014 - 22:21  (116773)

Agreed, it is very frustrating. However, in order to try to introduce more impartiality to the review I stuck to using these reviews, which have stated methodology, and use only the results for the Free versions. Thus, I am not judging them with respect to each test, but over all three labs for the previous three times the Free version was tested. I also take into account AV architecture, meaning default-deny and default-allow, and use that in my recommendations. I use default-deny being higher, but less user-friendly. That is why Comodo AV is rated number one (as my main criteria is protection) but Avast is rated just after because of higher user-friendliness and detection rates.

If you believe there is a better way to go about this please do let me know. I went through a lot of ideas before I came up with this one, but I also realize that there are issues with it.

Thank you.

by MidnightCowboy on 13. June 2014 - 8:59  (116758)

I've always been concerned about reliance on test results when choosing an antivirus solution but at least with the reputable labs you have access to the methodology. MC - Site Manager.

by MidnightCowboy on 4. June 2014 - 9:56  (116613)

I've had the latest FortiClient running on several machines for a while now, one of which is mine, and everyone including me is very happy with the results.

It's getting good results from AV Comparatives and VB for those who follow such things.

Be aware that the update process will kill you if you have a slow connection, but it's no worse than a lot of others.

Also, the stated Application Firewall is disabled unless you are registered into their FortiGate system.

The parental control/web filter is truly class leading and the configuration options are many, allowing for a considerable amount of fine tuning if needed.

IMO in combination with WinPatrol and say ZoneAlarm free firewall for those who must use something other than Windows, this is an efficient solution. MC - Site Manager.

by Chiron on 4. June 2014 - 13:53  (116619)

Thank you for pointing this out to me. I will evaluate this AV and consider it for my next re-write.

Thanks again.

by MidnightCowboy on 10. June 2014 - 6:25  (116704)

The updates for FortiClient are on demand (manual) which won't suit everyone but if your habits are such high risk that you need updates every hour then IMO you should be using Linux anyway. MC - Site Manager.

by andrew1879 on 1. July 2014 - 6:04  (117050)

I switched to FortiClient a few weeks ago too. The signature updates are automatic.
By default the software itself will only display an alert when a software update is available, but there is an option in File > Settings "Automatically download and install updates". Note that this option does not refer to the signature updates--which are always automatic in my experience--but to FortiClient itself.
So far I think FortiClient is worth a look - high detection rates, fairly lightweight and needs virtually no user interaction. The web filter is a nice bonus too. But I would like an option to not install its VPN component because it's useless for an average home user and it installs unnecessary virtual network adaptors.

by MidnightCowboy on 1. July 2014 - 7:31  (117056)

I'll need to take another look at this as soon as I have the time but the updates were certainly not automatic on my machine. Furthermore, the FortiClient 5 documentation (page 69) refers only to the use of the manual "update now" button, unless the software is being used in conjunction with their commercial FortiManager. MC - Site Manager.

by andrew1879 on 2. July 2014 - 1:19  (117072)

In the current version of FortiClient ( the UI has been changed so that there is no longer an "Update now" button. Version 5.0 also updated automatically for me though, except when my firewall (Privatefirewall) blocked it and needed some configuration to allow the various FortiClient processes.

by George.J on 2. July 2014 - 2:38  (117073)

Is there any offline installer for Forticlient?

by andrew1879 on 2. July 2014 - 4:13  (117075)

I don't think that there is unfortunately. At least not for the free FortiClient.

by George.J on 2. July 2014 - 12:45  (117093)

Allright, do they provide offline database definitions updates like Avast, Avira, AVG? Also I couldn't find a way to pause/stop definition updates...

by andrew1879 on 3. July 2014 - 0:01  (117102)

I don't know, sorry. I couldn't see it on their website. You could try asking at the Fortinet forums.

by Chiron on 10. June 2014 - 17:26  (116713)

Actually, for the purposes of this article I may still consider reviewing it, but without automatic updates it would certainly not be ranked too high. That would significantly lower the provided protection level.

Thank you for the additional information.

by wekslap on 1. June 2014 - 22:16  (116551)

I've been using comodo since it became top recommendation. other than seeming a bit slower than avast my previous,it seems to work fine.

my main query and slight worry about it is that when I run a ccleaner registry scan it always shows up a registry entry that cannot be deleted. HKCR\CIS.CisDebugInjector is this safe? What is it? can it be deleted?

by bo.elam on 2. June 2014 - 23:33  (116568)

Wekslap, about the registry entry, you don't need to worry about that. The key seems to be from Comodo and you are using Comodo. I remember experiencing something similar when I used Avira 9 about 5 years ago, the best solution is for you to exclude that registry key in CCleaner Options > Exclude, Click Add, add registry key. Doing this, CCleaner wont scan for that key or delete it.


by Chiron on 2. June 2014 - 13:42  (116561)

Assuming that entry only started showing up after Comodo was installed, it seems that it is likely related to CIS. As for why it can't be removed, I do know that Comodo protects many of its files, and resists even trusted programs, such as ccleaner, from removing them.


by rickybobby on 1. June 2014 - 19:04  (116549)

I like you list Chiron, and the update is right on spot. However, I would like share my view based on my constant AV installation / uninstallation process, if you don't mind.

Avast! => Was very good detecting viruses, but the other free antiviruses improved a lot. Also, some free-although-limited extras like the "sandbox" were removed. Expect some false positives

AVG => This is my AV for the time being. It had some compatibilty problems with certain programs, but nothing serious. Works on systems with low-RAM and does a great job removing scum such as OpenCandy while installing programs that contain it.

Avira => Good against viruses, but can cause some damage on infected systems. Its functions are very limited for such a big installation file.

Bitdefenter => Works effortlessly on the background and does a great job detecting and cleaning viruses. Its configuration options are almost non-existent, but has a small installation size.

Comodo => Great antivirus engine, maybe too good, as its Behavior Blocker can get too intrusive. It can become a resource hog depending on your PC configuration.

I just read MidnightCowboy's thoughts on the new 360 Security and I faced the same problems. He's definitely right on his recommendation to wait for it to get more mature before setting it as your default AV.

by Chiron on 2. June 2014 - 13:47  (116562)

Thank you for sharing your experiences. The difficulty in creating a ranking system, such as is used in this article, is that it can be very subjective. That is why I narrowed down what I believe to be the most important criteria, and evaluated the programs based on comparable protection level. I will, however, consider your experiences for adding more information about each product during my next rewrite.

As for 360 security, please do let me know if you believe it is mature. The scores for the previous version were quite good, and I am planning on adding it to the list, assuming the protection scores remain decent, once it is more stable.

Thank you.

by rickybobby on 7. June 2014 - 20:27  (116669)

Thanks for considering my suggestions, Chiron. Your list is great, and I really appreciate your efforts.

Warmest regards

by Chiron on 7. June 2014 - 20:54  (116670)

Thank you.

by MidnightCowboy on 31. May 2014 - 5:51  (116526)

A series of long and mostly off topic comments have been moved here to the forum. MC - Site Manager.

by Chiron on 31. May 2014 - 13:41  (116532)

Thank you.

by Anupam on 30. May 2014 - 7:03  (116494)

New antivirus.

SkyShield Antivirus:

by cavehomme on 17. June 2014 - 19:10  (116804)

I would not install Sky Shiled on my PCs. Why?

- New company / site since Feb 2014 according to Netcraft.

- Zero information on their website about who the company is and where they are located.

- zero reviews other than those placed by the company or its supporters.

Enough said, period.

by MidnightCowboy on 30. May 2014 - 7:19  (116496)

I like the way the "Learn more" button just scrolls you further down the same page with absolutely no other information about the product or where it comes from (unless I'm missing something?) :D MC - Site Manager.

by Anupam on 30. May 2014 - 7:28  (116497)

Well, information about the product is there, but not about where it comes from, or anything else regarding that matter. I didn't notice that... thanks for bringing this up. Caution needs to be exercised then, or maybe wait before more information about this product comes around.

by MidnightCowboy on 30. May 2014 - 8:09  (116498)

I certainly would not install this (at the moment) into anything I had not already consigned to the bin for other reasons. :D Could not find anything for it either over at Wilders which is usually the first place stuff like this appears. There is a "review" for it at Softpedia which states:

"It’s an appropriate solution if you just need a self-sustaining antivirus that does its job but on the other hand, if you might want to schedule a scan, grant permissions to certain apps or even view the quarantine, then you need to look for another antivirus.

All-in-all, SkyShield Antivirus might not be all that buffed up with features and well, it’s not that versatile, but it is a straightforward and user-friendly solution that can fit well on any system".

.... and then goes on to give it an almost 5 star rating for reasons I've yet to work out. :)

by Anupam on 30. May 2014 - 8:18  (116499)

I agree with you. I just saw the antivirus on one of the download sites, and just thought to share. I didn't give much thought on it. Should have :D. It's fairly new though, so it might turn up on Wilders soon enough, as more people catch up on it.

by Chiron on 30. May 2014 - 17:28  (116510)

I'll see about adding it to my article about How to Report Malware or False Positives to Multiple Antivirus Vendors:
but from what is available about this product it seems to be a far cry from any AV which I could consider recommending. Perhaps that will change in the future.

Thanks for pointing it out though. It's always good to see new players entering the field. I'll keep an eye on it.

by MidnightCowboy on 23. May 2014 - 18:20  (116393)

I had a quick look today at 360 Total Security which is the new product replacing 360 Internet Security "in the near future". I activated and updated the additional engines OK, including Avira, but on running the program, no notifications for scanned downloads or indicators as promised when entering a shopping site, despite all of this being configured in the settings. Can't find any info about which browsers are supported (or not) but I tried using IE11, Chromium and Pale Moon. Guess I'll come back to this once it's had a bit more time to mature. MC - Site Manager.

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