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.

Related Products and Links

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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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I should clarify this in the article as well, and I will during my next rewrite. I can use the results for CIS because the core protection, at least against any malware which makes its way onto the system, is identical between the two products. If there does become a difference then I will no longer consider the results for CIS to be comparable to Comodo Antivirus. I hope that makes sense. If you have any questions, or do not agree that the protection against malware on the system should be considered identical, please feel free to ask. Thanks.


Thank you for your reply.

All my questions have been resolved.

Your the BEST !!

Thank You !!

You mean, "You're the BEST !!"

Why does PrivDog extension get installed, even when I've deselected it from installation options of Comodo IS? Is this normal or a bug?
I'm sorry that I did not respond to this sooner. The PrivDog extension should not be installed if it was deselected. However, I do find that the area where this is deselected is confusing to find. That said, if you are sure that it was deselected, but it still installed, this sounds like a bug. If it is replicable please report it on the Comodo forums. Thank you.

well the avast 2014 is not that powerful in my experienced than the avast 2013 in terms of detection rates specially on worms! i have recently installed newly and updated version of avast 2014 on 3 different pc's however, the 2014 edition does not detect worms and their behavior on the computer. So why would I trust this antivirus program? worms are sometimes a kind of destruction to your files specially in flash-drives for it has a auto delete and auto hide components. fortunately I have been using Microsoft Security essentials for detecting almost all kinds of worms.

Every AV will have good days and bad days in terms of detection. However, I can tell you that nearly every test will put Avast far above MSE in terms of both detection and protection. That said, it is possible that Avast's detection of certain types of malware is not as good as that for others. Please let me know how you tested it against worms. How many samples did you use, and what was your methodology? Thanks.

I have been testing a few antivirus above and having a slow laptop (C2D 2.0ghz, 4gb RAM), I really care about the performance. And here is my take on each antivirus.

Since Avira implemented the cloud service, I have noticed some slowness (boot time and overall response time) compared to previous experience. Uninstall, and reinstall with cloud service ticked off seems to make it more responsive however it is not as fast as before.

For Avast, there is not much performance degradation on the new program update, everything seems working fine.

For BitDefender, it is very slow, and I still wonder why would people rate the performance as "high". My boot time increase for about 20 seconds compared to no antivirus installed after switching to Bitdefender. Try to give it a whirl, but the responsiveness is worse than Avira (high i/o activity).

AVG as usual, still slow however the recent version seems quite improve than before. Much better than Bitdefender but slower compared to Avira.

Machine with Panda Cloud seems to have the fastest overall response, with boot time only increase for about 3 seconds compared to no antivirus installed. However, my laptop is not 24/7 connected to internet, thus I have trust issues during offline operation.

Currently, in terms of overall performance and boot time impact would be:
Panda > Avast > Avira > AVG > Bitdefender

I have not tested latest COMODO due to time restriction (the last time I evaluate COMODO antivirus is in 2012), can somebody shed some light?

How much is the RAM usage and the boot time increment compared to other AV listed above?

Each AV will run somewhat different on different computers. Thus, I would advise checking Comodo Antivirus yourself and seeing how it fares. However, in general, I was planning on trying to locate somewhat reliable performance statistics for the AV software listed in this review for one of the upcoming updates. Once I have done that I will be able to supply more detailed information. Thanks.

Just my 2p-worth of experience with Bitdefender Free AV. After I installed it I could no longer print to my networked printer. The documents just sat in the queue and never printed. Uninstalled BD and all was well. I even tried reinstalling the printer after BD, but it still didn't work.
Decided to put Avira on instead and have had no problems.
I did a quick web search for problems, which only threw up issues with the full Internet Security Suite and its Firewall - which, of course, isn't part of the free AV prog. I guess I could have dug around some more, but life's too short.

That is a strange issue. I suppose the best approach, assuming you would like to try Bitdefender again, would be to ask that question in their forums. However, if you're happy with Avira then I suppose there is likely no need. If you have any questions about any of the other AV's listed in this review let me know. Thanks.

After trying comodo antivirus for only two days, i had no choice to uninstall it before my PC had had a heart attack. While running a full scan Comodo Antivirus brought my machine to a halt, the Quad core CPU was 100% most of the time. There is no doubt the spec of the software is pretty impressive for a free product, but be aware it may take over your machine while it takes an eternity to scan your drives . I have reinstalled AVAST which i have been using for years combined with comodo firewall. The CPU hardly moves during a FULL Scan allowing you to go about your business.

From my experience this is likely due to some sort of interference, or a problem which somehow occurred during installation. Please try reinstalling it by following the advice I give in this post: and let me know if that solves this problem. If it doesn't let me know. Thank you.

I run Comodo CIS on two fairly low-end machines (single-core 2 and 2.3 CPUs) and I've not found this problem myself for several versions now. Running a scan typically fluctuates between 10 and 40% rising sometimes to about 90. Later versions have the option to run scans as a background task as well. I've not found it to be noticeably slow compared to other scanners.

A few months ago I tried Comodo on my XP machine, and found I had to turn off the internet connection before I could boot it. Otherwise Comodo took over the machine, and just sat there doing who knows what (my guess: a download of the whole malware signature database, followed by a full-scale scan) that monopolized my computer and did not respond to any interrupts for hours on end. Fortunately that computer has a mechanical wireless on/off switch on the front so I was able to break in and try and tweak the thing into proper behaviour, but the mitigation was slight; I eventually wiped it in disgust. My experience with avast was nearly equally bad, just enough less offensive that, faut de mieux, I elected to tolerate it for now given the oncoming demise of MSE for XP.

Obviously, I need the best fortifications available constructed around my XP facilities. Equally obviously in the past few months there have been major changes in all the anti-virus offerings and how they work. Maybe things have improved.

Clarification is needed, too. I got an "update" notification from Comodo offering added features. But a close reading suggested (the weasel=wording and misdirection is shameful) that they were trying to sell me an upgrade, likely at exorbitant subscription expense. I could be wrong - but why are they playing this game in the first place?

I just want an antivirus that works, and don't mind running a selection of separate anti-malware programs should these be necessary. I know the internet is a dangerous place and will defend as best I can. But programs that take over and run away with my computer, or try con games with me, are not things I'm eager to take on - even with your recommendation.

Which version was this? I know that for V6 and V7 it only requires an initial update and then a quick scan. V5 used to require a full scan. Also, if the initial download takes a long time you can always manually update the definitions (directions are here) If you are having other problems, which it sounds like you were, I would advise reinstalling by following the advice I give in this topic: If you wish, you can try it again. If you run into any new problems, or have any questions, please feel free to contact me. I can assist you with this. Thank you.
The only pain with Comodo Antivirus is with manual updation of definition files. After downloading the bases.cav file, ther's no easy way to update the definitions. Although I tried moving the file to /Comodo/Scanners, the program failed to detect the definitions file, and upon checking for updates again, it started downloading the whole 170MB file. Previously using Avast, everything was quite easy. Anyway I'm still happy with Comodo IS. :D
Thanks a lot :D But who keeps import function inside "About" :{
Now that you mention it, that is a strange place. However, now that you found it is everything up and running correctly?

Hi Chiron,

I think there's a typo in your last sentence about the top pick:
... I do with they made the process simpler.
I suppose you mean: I do wish...

Thanks for pointing that out. If you see any more errors please be sure to let me know. Thanks again.
Now corrected. Thanks Geert for pointing it out. Demonstrates admirably one of the failings of built-in spell check. MC - Site Manager

@Chiron @MC
You're welcome.
Thanks for the work you put into this site.


Why do you say "the level of protection provided is not identical with the paid" in BD Free review?

Perhaps I am wrong. Did you see somewhere where it said that the protection was identical? If so please provide a link so I can check it out. Thanks.

From the BD Free Manual:

What is Bitdefender Antivirus Free Edition?
Bitdefender Antivirus Free Edition is an antivirus program designed to be fast and
to minimize user interaction, while sacrificing nothing of the malware detection and
removal capabilities that Bitdefender products are generally known for.

Also a BD staff confirmed in Wilders forum. His name is Iulika0069.
He confirmed BD free provides same protection as paid. The thread is huge, its hard to find the post. There are many post by him & you will get all the info about BD free.

I'll try to search through that later. It really is a huge thread. However, here is an excertp from the main Bitdefender Antivirus Free Edition page here: They say that "Bitdefender Antivirus Free Edition shares some of the revolutionary technologies that allowed our main product line to outpass major competitors such as AVG, Avast or Avira." I'm not sure exactly which technologies the Free version does not have, but seeing as they specifically state that technologies have been removed from the Free version, I assume that the Free version also would not protect the system quite as well as the paid version. However, when I have the time I will look through that thread and try to see if perhaps I am wrong. If you run across a relevant post before I do please direct me to it. Thanks.

The link you gave mentions all the features BD free has.
Active Virus Control
Intrusion Detection System
HTTP Scanning
Early Boot Scanning

The Wilders thread I mentioned, if you go through the thread, you will see BD staff confirmed on the above features too.

I think the missing stuffs in BD free compare to paid are the additional stuffs like, safepay, wallet, rescue disc, parental control, etc...

I will try to find few important info posted by BD staff on the wilders thread & let you know.

I did notice that. What I'm not sure about are the further details. These are things such as, are signatures available just as quick to both, is the site-blocking feature updated just as frequently, is the heuristics used just as effective, is the cloud backend just as effective, etc... Marketing often just lists that both have the same features. The issue often lies with how effective those features are for both. Does anyone know about my above worries? Thanks.