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:

18-12-2015 - New article editor: Added products to be reviewed

Products to be Reviewed:
  • Avast Free Antivirus
  • Avira Free Antivirus
  • AVG Antivirus Free
  • Baidu Antivirus
  • Bitdefender Antivirus Free
  • Clearsight Antivirus
  • Comodo Internet Security Premium
  • Fortinet FortiClient
  • Nano Antivirus 
  • Panda Free Antivirus
  • Qihoo 360 Total Security
  • Roboscan Internet Security Free
  • Sophos Home Antivirus
  • Windows Defender
  • ZoneAlarm Free Antivirus + Firewall


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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I downloaded the installer today from the link on our page. The file was: cav_installer_3272_7b.exe (204.1 MB). I selected the language and unticked the options for cloud based behavioural analysis and anonymous usage statistics. I then chose "customize installation" and unticked the options for GeekBuddy and the Comodo browser (Comodo Dragon was already installed on my system which is why it appears in the program list) Proceeding with the installation I also unchecked the options for using Comodo DNS and the search engine change. The result was a clean install with nothing else added or changed. If you research this properly you will find that GeekBuddy can also be included with a third party wrapped installer, so if you obtain the program from a different source, it is still possible for this to be installed even though this option in the Comodo install process was denied. MC - Site Manager.
This happened to me once in the past, even after choosing custom options, GeekBuddy still got installed.

Thanks George and MC.... it's obvious that we don't live in a perfect world so I can cop the odd glitch from software that's free.

About two months ago, I had to wipe my computer and reset to factory specs, after a virus-related issue I just couldn't get rid of. (Happens about once a year for me. Means I'd like to see the death penalty for all virus writers.)

For the last two months I have been letting the built in trial version of one of the companies that doesn't have a free virus option cover my system, while backing it up with Spybot (for the immunization protection), Ad-Aware (just because it has been one of my back-up options for ages) and MalwareBytes because it cleans up almost anything.

Today, the trial software (which still had four days left) turned itself off, and turned off my firewall, too. I did scans with all four products, none finding anything, removed the trial virus program, and installed BitDefender as my 'active' program, with the other three still being regularly used manually to scan for problems.

Considering adding Avira as just another 'try it once a week or so, looking for any problems.'

Since MalwareBytes is almost always my first thing to throw at anything that acts weird, most of the others never get a chance to find anything, but I still lake the extra options to try and make sure everything is good.

Any thoughts or comments?

It is never advisable to install more than one antivirus program. There are umpteen posts from reputed sources on the web about this, these being just a few. Secondary scanners that are designed for this purpose are fine, but there are also risks associated with installing a second real-time product and then disabling the active protection. In any case, it is always better to prevent infection rather than trying to clean up after one. The best strategy therefore is to understand how and where from you became infected previously and then tailor your PC usage to avoid further repetition. Having 10 scanners on board still won't help if there is an underlying usage trend to become infected. You might find these articles of interest. MC - Site Manager.

I have been using Panda for some months without issues, but yesterday it updated itself to a new version with a different name. After this, my Privatefirewall could not start anymore, even after a new install (PrivateFirewall Ndis Filter Installer - Install Error 0x80870002).
Looks like the new Panda is incompatible with Privatefirewall.
After removing Panda, Privatefirewall is working fine.
I'm posting this information in case it can be useful to someone else with the same problem.

You could have tried shutting Panda down while installing or move the new PF installer to a folder that you can exclude from Panda.

Have you reported this issue to Panda so that they can investigate and fix it?

Which acceptable av uses the fewest resources, especially memory?

The differences between them might alter every time a new program update is issued.

It also depends on whether you use all of the offered components, I don't.

Last time I checked, BitDefender Free had the lowest usage but it was also the least configurable. My choice is a custom install of Avast Free, I just select the parts I need and then configure it to my needs.

Might do well to remove Panda AV altogether from the list.

An AV specialist that actually identifies itself as a virus is a joke -- though not for the many, many thousands yesterday who were comprehensively sat upon by the blasted Panda. Including myself.

I've run Panda Cloud AV ever since it was released. I'm also aware that stuff happens. But an AV specialist making so huge a blunder as this has me worrying just what kind of sloppiness goes on there -- and what kind of disaster might come along next. 'Bye, Panda. Some one-off glitches are waaay too serious to take a chance that they won't happen again .

Panda of course are not the first AV listed here to have suffered a similar fate and no we will not be removing it nor would we recommend users running Panda to change. In any case, a remedial fix was issued almost immediately. MC - Site Manager.

I had remove Comodo after reading the Privdog that come with it.

Although the Privdog version bundle is not the version that is vulnerable but I do not trust Comodo anymore, specially both Comodo and Privdog are same CEO, and I remember clearly that I had dis-select Geek Buddy, Privdog when install Comodo, yet I still find the Geek Buddy Icon on Desktop and Privdog secretly install.

Just google "Adware Privdog worse than Superfish"

Two articles that discuss this are:

"Privdog is Superfish all over again" - and,

"Don’t use Comodo, Their Crapware Completely Breaks the Fundamental Security of the Web!" - .

A new version has just been released. "This new version addresses issues with keys; keys sizes have been increased to 2048 to comply with a higher standard and improve browser compatibility. Existing users will be upgraded automatically or users can download the update. As always we recommend all users update to the latest version. In the next few days we’ll release version 3.1 with additional features allow users to disabled the HTTPS inspection if they choose to do so. We are also implementing an HTTPS Threat Vector list that will automatically bypass HTTPS inspection for the vast majority of safe web sites". MC - Site Manager.

While I really like the Comodo apps, I do think its write up should note its "extra" things installed if you do not catch the tiny text (a not obvious, easily detectable way to do that) leading to a separate screen to exclude them. Such is noted for some of the other products.

A Geekbuddy component is one of the extras installed if you do not notice the small text under a BIG button to proceed, and there is another extra I do not remember.

5 Common Myths about your Antivirus A really interesting video from a website that I visit daily. Myth 1: Detection Rate is Everything - False Myth 2: If an antivirus detects a threat as being malicious, the file is definitely malware - False Myth 3: Paid is always better than Free - False (for home) Myth 4: You cannot use 2 antivirus at the same time - Usually True (but completely misinterpreted) Myth 5: More "Security" the better - False
Qihoo Internet Security 5.0 released. They don't update the IS version webpage though, it still shows at 4.9 The Total Security is at version 5.2 Stable and 6.0 Beta, but it's good to see the lightweight Internet Security version is still getting developed.

I have been using avira for ages but recently they have overdone it with the offer pop-ups. I tried comodo but you have to teach it everything from scratch. So I'm thinking to try panda but I also don't like much automation (I know! I'm hard to satisfy). Actually I find avira fine in configuring and automation. Can anybody please tell me whether panda is more automated than avira? I mean I would like my AV to ask me of what to do when something is detected. Can this be configured in panda?

Your comments, especially regarding Comodo, suggest a confusion between the normal antivirus and HIPS functions (where included) of security programs. IMO if someone is capable of determining the correct actions to take for every event, then a correctly configured standalone HIPS such as Malware Defender could be used instead of an antivirus program. In reality though a broad spectrum antimalware solution containing multiple detection methods will always be the preferred solution although this inevitably involves a degree of automation. Panda scores highly with both AV Test and the AV Comparatives Real-World Protection tests. Yes it is more automated than some but IMO this is how it should be, especially for normal home users many of whom will not have the knowledge, or desire, to operate their security programs manually. MC - Site Manager.

The thing with comodo is that if I disable HIPS and sandbox the windows action center gives me a warning that no antispyware program is active but only antivirus.
I don't want to disable WAC, but I find HIPS and sandbox personally annoying and not very useful to me (the way I use my pc). With avira I had antivirus and antispyware all in one, running smoothly with only the necessary to me alerts. So I was wondering if Panda is similar to avira in that sense. It worries me that this article says that in auto quarantines items that finds them suspicious. That is because I have used other AV software in the past that have quarantined or deleted items without a warning and it was very difficult to restore them cause it would immediately put them back to quarantine and they were not very configurable. So before I install panda I'm trying to get some more information on whether it has this kind of behavior. Thank you for the advice.

I am not very familiar with Panda. Just a tip: you can disable the offer pop-ups by making a blocking rule in Windows firewall for Avira file ipmgui.exe.

Thanks a lot for the tip. If nothing else works I'll go back to avira and try it.

I dumped AVAST, as it insists on installing Chrome, V10 has lots of problems, lots of ads, even in the Pro version, which to me is unacceptable.

In my search for a replacement, I chose Panda Free. Works great, has great detection rates from all agencies, is clean and simple. You can turn off the "news feed", auto-quarantining, etc in the settings.

You can have it ask what to do if a virus is found.

There aren't as many settings as AVAST, but all the basics are covered in a very logical layout.

I'm running it on Win 7 Pro x64, Win 8.1 computers.

Thanks for the comment. When I tried Panda some time ago I couldn't find any setting to disable auto-quarantine, although I thought I checked all the options.

Possibly I overlooked it or there has been an update but thanks for the info.

Avast does not insist on installing Chrome at all. I have been using Avast since years, and using the latest version too, and I have never come across this problem. It does offer Chrome during installation screen, but it can be opted out without problems. Also, there is no DNS shield in Avast. And I haven't encountered lots of ads.
I suspect that the poster is reporting real issues but some of them may not relate to the free version. There were lots of problems reported with Avast ads and automatic installs of Chrome but as far as I know this related to the paid version only. There is no "DNS Shield" but there is "Secure DNS". Avast uses the word "shield" for several of its other features including "web shield" and "mail shield" so the poster might have misnamed it.
Thanks Remah... you are probably right. But, if the comment indeed applies to paid version, then it is out of context as Gizmo's is about freeware only. In that case, will have to edit the comment. Let's see.

To All,

I apologize for including comments about the paid Pro version of AVAST. Please edit as needed.

I have both installed, Avast free at home and Pro at work and got them intertwined in my post.

I have never has issues with Open Candy and the free version using the Software Updater. In fact, that is a great feature of Avast, one that I would miss if I switch to Panda.

It is not DNS Shield, it is Secure DNS and is only in paid versions.

Avast will default to checking the Chrome installer on every update.

It displays ads in the status screen.

This is not false information!!

Thanks for the clarification :). I have now edited the post suitably. Yes, that problem is there with the Chrome installer I guess, but as long as you are able to opt-out, I guess it's okay. I perform a fresh install for every version anyways, so I wouldn't know about other way. I have found ads to be okay with Avast free... not intrusive, and I am okay with that.