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. However, 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 eventually. 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 due to unintended conflicts. For my advice on how to compensate for these weakness of antivirus products 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 arsenal.


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 I do of course admit that 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.

Recent Changelog:

10/7/2014-Re-inserted explicit statement mentioning that I am a volunteer moderator (not employee) on the Comodo forums.

10/9/2014-Linked to instructions on how to make sure Bitdefender Free can be installed in English, and added MSE to list of unsuitable AV's.

11/14/2014-Added additional information about Bitdefender Free.

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. My criteria is entirely based on protection, not cleaning. Therefore, if you believe your computer may be infected please first see my article on How to Know If Your Computer Is Infected before continuing to read the rest of this article.


I have located reputable 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 spanning back over the last two years. 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 (which has the exact same protection for its Free and Paid versions), are often quite different from those for the Free versions. Many marketing teams try to cloud this difference, but for the purposes of getting the most reliable information I am strict about this. Unless it can be explicitly proven that every protection mechanism is exactly identical to the free version the results for paid products are not considered in this analysis.

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 (CIS), which is also free and includes a firewall in addition to all other components which already come with Comodo Antivirus.

Firstly, I will note that I am a volunteer moderator (not employee) on the Comodo forums. However, this is certainly not the reason I chose this for the number one position. 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. This is because it maintains a white-list of known safe applications. Then, all unknown applications, which include all unrecognized malware, will be sandboxed and isolated from the rest of the system. Thus, this product provides very strong protection against even zero-day malware.

Comodo Antivirus also uses the cloud to facilitate the detection of the most recent malware, as do many other Free Antiviruses reviewed in this article. 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, please see my notes in the Quick Selection guide for advice on how to avoid unwanted software during installation.


Panda Cloud AntivirusPanda Cloud Antivirus is an excellent choice for average users, who may find Comodo Antivirus 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. The protection offered by this product is very strong. However, do note that it will auto-quarantine files which it believes to be dangerous.




Avast! Free AntivirusAvast! Free Antivirus 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 Web of Trust, but the script malware protection can prevent certain browser exploits, a feature not available in any of the other free AV's reviewed.

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. My advice would be that if you want to install Avast you should not use the Software Updater tool.


AVG Anti-Virus Free EditionAVG Anti-Virus Free Edition is also a good 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).





360 Total Security is also a good choice for average users. Although it has gotten some very stellar reviews, the results I found from looking at the results from the testing agencies referenced earlier in this article show that the protection it provides is roughly the same as AVG, but certainly not as effective as Comodo, Panda, or Avast. This product uses multiple antivirus engines to detect malware. It has cloud protection, and also uses the Avira and BitDefender engines, although these are not enabled by default. For more information about this antivirus, see the separate article on this page.

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, Avira provides 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 very similar the commercial product, although there are some tweaks. However, the level of protection provided has not been shown conclusively to be identical with the paid version, which is why I did not use the results for the paid version in my analysis. Bitdefender Free has both local and cloud-based definitions. Thus, users always have access to the most up-to-date definitions. It also has an effective heuristics engine, and uses a component called the Active Virus Control to monitor applications in real-time for suspicious behaviors. In addition it also has a webshield, which seems quite effective at protecting users from both malware infested and phishing sites.

The user interface for this product is very minimalist. Thus, it may be attractive for novice users, although more advanced users may be frustrated at the lack of customization. However, it has no offline installer, and it also requires registration to continue using it past 30 days. 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. Also, note that if you are having trouble getting Bitdefender Antivirus Free Edition to install in English please follow the steps in this post.


Please help us by rating this review

End-Note: Please note that I also looked into Forticlient , Kingsoft, and Microsoft Security Essentials. However, I found that the protection offered by these products is subpar. Thus, if you are considering using Forticlient or Kingsoft I would strongly recommend that you instead consider another of the products reviewed in this article.

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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). Also, Comodo Secure DNS, which is offered with Comodo Antivirus during installation, tends to have many false positives. Thus, I would suggest that you untick the option to Enable Comodo Secure DNS during installation.
Version 6.x
32 and 64 bit versions available
Unrestricted freeware
There is no portable version of this product available.
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, I would suggest that you untick the option to Enable Comodo Secure DNS during installation. It tends to falsely block many safe pages. 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.
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: Forum:
Windows 2000, Windows XP, Windows Vista, Windows 7, Windows 8.x, Mac OS

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.
Forum for support
Windows 2000, Windows XP, Windows Vista, Windows 7, Windows 8.x

360 Total Security

Runs as a stand-alone program on a user's computer
Contains many engines for malware detection.
Avira and Bitdefender engines are not enabled by default.
32 bit but 64 bit compatible
Unrestricted freeware
There is no portable version of this product available.

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, no offline installer, requires registration after first 30 days
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.

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


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Well am back to using 360IS again. The reason is 360TS requires more resources on my system. The TS version uses around 150MB RAM while the IS version is very lightweight, using only around 30MB. Additionally 360TS adds other features like SpeedUp, Junk CleanUp etc, which aren't actually required for me, although it might be useful for others. While 360IS is clean as a whistle, guess it's the best antivirus I've ever used. Sadly the product isn't updated frequently like 360TS version. :( For a comparison betweeen 360 IS and TS in detection check this video review. If you want to watch various community video reviews, you've got 360TS MazaiTest 360IS Review 360TS viktik 360TS without BD and Avira engines 360TS yigido Overall excellent results from all sides :)
I agree with your findings although with an i5 and 8G in my dual booted desktop I'm not too bothered about resource use for anything. Unfortunately, 360IS is being discontinued in favor of 360TS so I'd rather use something that is being fully supported. MC - Site Manager.
360IS isn't discontinued. It just had an update today :D It's just that they are concentrating more on the TS version.
Not yet it's not, but their plan is for TS to replace 360IS, although they haven't said when. MC - Site Manager.
Honestly performance matters to me. Here's my findings 360TS is much heavier on the system than IS version. Idle Memory Usage 360TS - >150MB RAM 360IS - <40MB RAM Scanning Memory Usage 360TS - 320MB RAM , high CPU usage touching upto 95% at times, Disk Usage is also very high 360IS - <60MB RAM, low CPU usage less than 25%, Disk Usage very low. You can see the difference. :D It doesn't matter if 360IS doesn't get product updates, I think I'll continue to use it. Maybe I'll stick with TS version on my gaming system. Still it's too heavy.

Please consider Qihoo 360 internet security:

Very well reviews product in

Thanks for doing this.


Am back to using Qihoo 360 IS, and it's been excellent. Excellent independent lab test results, very light on resources and clean installer (which is not the case with most free antiviruses). The Total security version is too much for me, as it also includes Avira engine excluding the BitDefender engine, which is not needed for me. But overall, a perfect suite. Moreover, it's good to see that Avira is offering a clean installer, which was not the case in the past. And also it's lab results are among the best. Had to switch from Panda as it was slowing down my system to a crawl :(
Update: It seems that the company has switched from 360 Internet Security (IS) and is favoring the Total Security (TS) version, as the last IS version dates back to January. So far 360 Total Security has been amazing for me. Works great as an antivirus and as a total security suite. Great performance, high detection, better zero day expolits (registry, files & system protection), keylogger detections, support and frequent updates, makes it awesome. By the way am using only the BitDefender engine, but even with Avira engine enabled it still seems very light. But I don't wanna go around and update Avira engine, so not using it.
Qihoo is not a bad choice at all. I'm also happy to hear it's light on your system. From what I have heard Panda is generally light as well. However, the heaviness of an AV is always, to an extent, system specific. Thus, you may find that when you get a new computer it is Panda that is lighter and Qihoo which is heavier. Thank you.
Honestly I expected Panda to be lightweight considering it being cloud antivirus. But the results just mirrored the lab tests at AV-Test with Panda rated lowest in performance, and lower than other Free antiviruses at AV-Comparatives for performance. But like you said, it also depends from system to system.
I will be considering them for my next major revision. Thanks.

It has been a long time since someone suggested Kingsoft Antivirus 2012 to be taken into consideration as possible antivirus solution. (see: and (

Few months after that there was a quite interesting discussion about the possibility to run Kingsoft Antivirus 2012 alongside other AV without conflicts. This discussion did not end very well meaning there was no clear conclusion to the matter. (see:

I come back here today with Kingsoft Antivirus 2012 (Cheetah) SP5.7 ( because i have been testing it for a while alongside KIS2013 on a pc with Win XP and on a pc with Win 7 64. I can tell you that i am quite impressed. No conflicts or compatibility problems so far. It is a cloud based antivirus, very light, with useful features, ability to fix vulnerabilities, USB defense function and it claims to be "Perfectly Working with Other Antivirus, Provides Outstanding Protection to End Users.". Although the software itself doesn't update frequently, the virus libraries do.
An interesting fact is that the company that makes the software is Chinese and apparently is no other than the guys from Cheetah Mobile that make known apps like Clean Master, Battery Doctor and CM Security for Android.

I just thought maybe we should give this one, another chance.

[Moderator's note: Link to non-English site edited out. Not allowed as per site rules.]

Thanks for pointing this out. I will look into Kingsoft for the next update.

I've tried Comodo Antivirus and Avast and could not get either of them to install on XP SP3. Comodo was the worst. Three times I got to the 71% point (it also stops and reboots your computer at the 43% and 51% marks) and it told me that it failed to install and to install it manually, but how in the hell do I do that?

Then the 4th time it told me it was installed, but it wasn't. The only thing it installed was it's geekbuddy software, which apparently is the only help available for the free version. I have to say, both Comodo and Geek Buddy are rude and arrogant and want nothing to do with people who install the free version.

I'm now about to try Panda's Antivirus. One of these HAS to work, no?

I'm sorry to hear about this. It sounds to me like there may be an issue with your computer. Perhaps another program is actively interfering, there is some sort of corruption, or remnants from a previously removed software are interfering in some way. If you make a topic for this in the forum, and send me a link to it, I can try to help.

FYI, I just visited the Comodo site using the link provided in the article. Download page states that Comodo free AV is for "Operating System: Windows 8, Windows 7, Vista", but nothing about WinXP. So I would not put it down to a computer problem - it's the second time this week I've run into this situation (I have a laptop and desktop w/XP, a desktop w/8.1). I'm sure that this will increasingly be the case, and wonder how many of the other AVs listed in the article no longer support XP. (No disrespect meant to the author - things change quickly.)

Thank you very much for pointing this out to me, and I very much do encourage that any reader who notices an issue brings it to my attention. I do keep track of all issues reported, and, if possible, these will be addressed as soon as possible. For this situation, I have edited the Quick Selection part to now explain this situation. There is an issue where there are significant limitations to Windows XP x64. These are such that if you are running the 64 bit edition I would advise that you use a different AV instead. However, Windows XP x32 should work fine. Please let me know if this answers your question, or if you have noticed any other issues. Anything you can bring to my attention would be appreciated. Thank you.

I guess you've been a bit unlucky - I've run CIS free for two or three years now with very few problems, although I do always install onto a clean system.

I've not tried GeekBuddy but the Comodo forums can be helpful.

We encounter these issues all the time with a variety of products and they are always local, due mostly to corrupt system files or the incomplete removal of other security software. MC - Site Manager.

avast FREE ANTIVIRUS now comes with OpenCandy.

"OpenCandy is integrated into SoftwareUpdater since a couple of months. We use it to offer additional software to our customers in avast Free under some conditions. It helps us paying for the traffic caused by Software Updater in Avast Free." (June 2014)

Thank you for pointing this out to me. I have now added a warning to the article.

Your warning: "Take care to avoid the default inclusion of the Chrome browser and OpenCandy during the install process by using the custom install option" (accessed 2014-08-24). That has been bothering me. :)

It would be very unusual to be given the option to reject OpenCandy. What you can reject are the downloads suggested by OpenCandy, but those come only AFTER OpenCandy itself has been installed, assigned you a permanent identifier, snooped through your stuff, phoned home info about your computer, your software, your geolocation, etc. It then selects downloads based on that info and on its previous interactions with you.

Last I checked, the user could avoid OpenCandy by not including the Software Updater component when installing avast or by removing it later. Note that Software Updater is not the avast updater.

the other thing: The OpenCandy offers are not made, or not only made, during the installation of avast. They come when the Software Updater functions, as long as it is installed.

According to Open Candy's own information, the OC component itself installs nothing on your system unless you accept one of the bundled offers. I've checked this for myself and it's true.

What happens is that when you run an installer that includes OC, the installer runs a dll which activates the bundled offers.

If you refuse all the offers then the dll is terminated and deleted after the original installer completes and nothing is left behind. I've also tested this for myself.

However, if you accept any of the offers then OC will install an auto-updater along with whatever offer you accepted.

The OC dll will "phone home" anyway, unless you block it, with the following information;

"A. Operating system version and language, country location and timezone of the computer running the installer, and the language of the developer’s installer
B. That the developer’s installer was initiated, and whether it was completed or canceled
C. Whether any third-party recommendations were made and if so, whether they were accepted or declined
D. If a third-party recommendation was accepted, whether the recommended app’s installer has been downloaded and the installer initiated
E. That the recommended third-party installer was initiated, and whether it was completed or canceled."

Note that the OC dll can be intercepted and blocked anyway, by programs like CIS.

LOL. The link removed in the paragraph below because of the bad WOT rating was to OpenCandy's FAQ; accessed accessed 2011-03-27.

Although you might like to think it's funny, our site rules are designed to protect visitors from potentially harmful links. Of course there are grey areas and situations when having a bad WOT rating does not present a hazard, but once we begin to make exceptions the whole system becomes meaningless. We do however expect members to read the rules before posting and abide by them for the benefit of the community. MC - Site Manager.

The comic element was the entrance of WOT in this particular conversation, in a rebuttal of the claim that OpenCandy is benign. The opportune arrival of reinforcements. I apologize for the unclarity.

I got the joke and enjoyed the irony too : )

I stand by my comments re; OC in general but fair cop, I hadn't properly looked into the situation with Avast in particular.

Not sure why anyone would be comforted by the fact that the dll is removed, when (1) the snooping has already been done at that point, (2) it leaves a permanent identifier on the computer, what OpenCandy used to call a "non-reversible identifier" [link with bad WOT rating removed as per site rules], and (3) its dossier on you is kept remotely.

Thus it is, or was, FALSE that "nothing is left behind."

In any case, you are describing the typical case in which OpenCandy comes with an INSTALLER. This is NOT the case with avast.

The dll is in fact NOT removed in the case of avast (not that it matters). You may "verify" that via the avast forum thread linked above. It remains and gets triggered repeatedly by avast's Software Updater component (which is something akin to the Secunia Personal Software Inspector).

Sophisticated users can block OpenCandy, certainly, but those are likely not the users seeking recommendations for free anti-virus programs. Also, the presence of OpenCandy gives insight into the values and ethics of the avast company.

360 Total Security Rocks!

It's like McDonald's "I'm lovin it!"

Yes I realize it is new. I've been on the net since all the others were new also. I too like to live dangerously.

* Patch windows with Windows Updates.
* Built-In System Cleaner.
* Built-In Start Remover.
* Built-In Sandbox. (similar to Avast)

One of the best guis I have seen in a while since others mucked theirs up. You ever try changing the detailed settings in newer versions of Avast?

It might just be me but it seems my machines run faster with 360 Total Security on. Probably because of the patches applied. It seems to find patches that Windows Update did not find.

* I have not run it on a purposely infected machine.
* It did remove startup items I did not want removed. (They were easily restored)

I would recommend only for an Advanced user for now. We don't know yet if their system cleaner is going to destroy something important.

Lenovo R60 Windows Vista 32-Bit
Acer Aspire 5532 Windows 7 Pro 64-Bit