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.

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

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.

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

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.

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

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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Average: 4.3 (2084 votes)


Please, consider adding Lavasoft's Ad-Aware Free Antivirus to your review. Although I haven't installed on my PC yet, I saw some very good results detecting and blocking internet viruses and those nasty USB infections. Couldn't find a detailed review or a lab test, though. A good review from you, would help to make things clearer.

AV-Test is not very good, they don't do much testing or use many samples and only score out of 6, they don't offer reports or show you their testing methods.

AVB100 only tests for the most common 100 viruses in the wild (WITH NO FALSE POSITIVES) and believe me i would rather be told and find out myself if its fake than them one slip through.

AV-Comparatives is a whole kettle of fish, they are certified by ISO and EICAR (others aren't) that their test procedures are solid, they also write up multiple page reports on the tests, perform many tests in comparison to the others and also score properly aswell as doing lots of various testing using 100,000-200,000 infections per test (for File Detection Tests) then you have Real World Tests, Heuristics Tests, False Alarms Tests, Performance Tests, Malware Removal Tests, Anti-Phishing Tests, Parental Control Tests, Mac Security Reviews, Firewall Reviews, Linux Security Reviews, Mobile Security Reviews, Business Security reviews -> where else do you get all this in multi-paged PDF reports that also show their testing procedures.

as it stands the best Free Security in my opinion is Avira (FREE) along with Comodo Firewall (FREE) and WinPatrol (FREE) - nothings going to get past that lot...Avira may not have much too look at and its a shame that it gets 3/5 on here as its about protecting your so Avast looks pretty and has extra options, but it doesn't protect your PC more than Avira - Avira has constantly been top for the past year or 2 for detection, real world protection, performance and False Positives.

[Moderator's note: irrelevant content about commercial software edited out]

Where exactly are you drawing your data from because over the past year Panda Free has consistently outperformed Avira Free regarding protection. MC - Site Manager.

Regarding Panda, could someone clarify what this means - "it will auto-quarantine files which it believes to be dangerous"
When it does that to a file that I do not want quarantined -
- do I get a 'heads up'
- and is it easy to undo the quarantine ?
I am leaning heavily towards installing it in my main PC, depending on the answer to those questions

I had used Avast for years, but it was getting a bit wearing.
I tried another one a few months back. Can't recall the name, but it is well known, and gives us 1 year free.
None of my PCs are new'ish, and are a mixture XP and W7.
I find networking somewhat painful, mainly with W7 being too 'nanny'.
When I installed that 'what was it's name' antivirus, my networking got much worse.
After I uninstalled that 'what's it's name', my networking returned to it's slight PIA state.

I am currently running with no antivirus (3 weeks), whilst deciding what to go with.
I can reasonably get way with this, by being careful in emails (I always am), and using FF with NoScript.
All those minimalistic Chrome lovers out there that do not use 'FF + Noscript' are unwise (I tempered that a lot)

Although I do not think only Panda does that, restoring automatically quarantined files is as easy as clicking on the main inteface button on the top (the whole interface looks like the new Windows start Interface with the squares) and then clicking on the Quarantine's "View Details" button. There you will see all the quarantined items and you will be able to restore them. If the folder the files were does not exist anymore, it will move them to a "Lost and found" folder. If it can find the folder, restoring them will also tell Panda the files are harmless so it will not redetect them ever as malware.

Actually you can always go in settings and switch on the option for the antivirus to first ask you before neutralizing a harmful file.

I am sorry if I made it sound confusing, but I can assure you it will take seconds for you to restore your files.

I consider Panda one of the two best lightweight Antiviruses and suggest it to people that want an antivirus with options. For friends and users that just want an antivirus that will kill anything and they will never care to change settings, I suggest Bitdefender. It will brutally quarantine anything that it believes it is harmful, be it you like it or not.

Both of them though have the option for the user to easily open the quarantine and restore the file.

Thanks for taking the time to respond.
I will give Panda a go


Hi, am the new editor here. This article is pending a major update for the New Year, so it's not been updated yet. Chiron, our previous editor left so I've big shoes to fill in. Unlike our previous editor, my results wont be considering the accolades that antiviruses have been getting at independent lab tests because the authenticity of these tests cannot be confirmed, as they don't show you proof. So I'll be doing my own malware tests on a virtual machine to consider the overall effectiveness of antivirus software. 

That being said it's finally the users choice to choose what kind of protection that they need, because no matter what antiivrus software you use, it's a safe bet that you will be protected unless you are deliberately calling for trouble. 

Practise safe computing habits, and stay safe. 

--- George.J (Editor)

So are we to assume that one or all of the independent testers are lying or their methodology is somehow irrelevant to how I use my computer?

Maybe for instance you can explain how relying on AV-Test results is bad for me or other users?

I just hope we are not going down the YouTube track of chucking a bunch of URL's at something knowing that in a few minutes they will have disappeared and then ranking product protection qualities based on their detection?

It's also worth mentioning that a stack of malware can recognize when it is being launched in a virtual environment.
MC - Site Manager.

The above comment was not to say that the reports made by these labs are false, they are just unreliable. As for being authentic or not, all I can say is that One Man's Meat is Another Man's Poison. Everyone is entitled to their opinion about the tests but the more I see BitDefender and Kaspersky up at the top in the Performance section, when they are infact heavy on my hardware, leads me nowhere. Also the Real-World protection tests at labs are conducted with just 1600 samples (which any YouTube user can test with) that only represents a drop in an ocean filled in malware.  
Now coming to comparing these results, on a personal basis these tests can be judged reliable, if each independant laborotory adhered to these 3 factors: 1-having the same software configuration 2-having the same hardware configuration 3-having the same malware database. Then it makes sense to compare the tests indicating the various parameters like scan times/data rate which are influenced by hardware/software config. There are many other factors that determines the results like hardware paramters (compatibility, OS updated or not, softwares being used), disaster management (backups, virtualization), browsing habits, human factors (social engineering) and all these are pitted against the World Wide Web, a real-time library of viruses, different kinds of malware and zero day exploits. Moreoever the information about malware used in testing isn't mentioned, and hence with a reasonable expectation we can conclude that the tests are conducted on a different database with different results. I'd say to take these results with a grain of salt. 
It's likely the paperwork done by these labs can be tampered without any basis and add to that the reputation of a well known organization is also being involved. Nevertheless, in short the real-world test thats been conducted by ordinary users is considered far better because now we can see the overall strong points of the products and also the product is getting tested on a wide variety of different hardware/software/malware specifications. None of the Big shots like Kaspersky, BitDefender, Avira and others might be coincidentally consistent at the top due to these common tests at the labs, but who knows?
Which leads us to this, whether it be the independant tests or the standard video reviwes at Youtube, both should be taken with a grain of salt. Simply because every product has different technologies to capture malware, having a good detection in one test, doesn't mean it is great, because there are so many samples out there and with many more coming in a daily basis it's impossible to detect them all. IF one vendor comes first, the others who didn't might detect samples that the winner doesn't have in its database. 
If anyone wishes to test a security product it's important to know how different features works and start from there, leading up to the advantages and disadvantages. If Comodo may focus on behavioural analysis, ESET might focus on static (detect prior to execution) analysis. Now this if not taken into account in a proper way, it will simply make a product look bad when it's not, if it's actual strength is used as an advantage. Someone tests a security product and concludes that it's good in protecting the system. When an independant lab does this the results might be the opposite. Now we've the same statement being used in both ways. None of these tests will show if a product is really good or bad, cauz individual products react differently in different situations and across various samples. 
To conclude, the best way I can find is to test out different antivirus and finally decide which one is that you're most comfortable using. However we see it, no matter whoever these lab tests promote as winners, it doesn't mean they are the best- the real truth is that there is none.  We as an independant review site have our own ways to test our products, and not being influenced by the outside world. I rest my case. 
OK, so let's take the "opinion" part out of the equation otherwise we'll also end up disputing the news value of CNN v Fox but what about my question regarding testing in a virtual environment as opposed to a live machine connected to the real world internet? MC - Site Manager.
I agree that there have been various bugs that malware could manipulate to bypass virtual machines, but this least worries me in standard malware databases. I feel this is more on a corporate level probably, as a lot of game servers are run inside of virtual machines in large quantity. Now, if malware could be custom-designed to bypass lets say a VMware virtual machine on a Windows/Linux server, or possibly even Virtual Box on a Solaris and other systems but I doubt that would be the case. 
From the way I see it, there is a pyramid. This one goes from government made and developed malware and techniques down to consumer level. Business, Corporate etc. are in between. Business as in companies like the now extinct Blackhole create exploits and the various new ones that I don't really pay much attention to. 
I guess if you were downloading a fake crack over p2p sites, then that's actually calling for trouble and having a higher chance of being something dangerous than on a malware database, that's my opinion at least. 
My technical knowledge might be limited to understand the deeper aspects of all questions and finding answers to them, all I can do is a give an unbiased review and learn something new along the way. 

Trust online is something harder to get than it is in real life for sure. I am not paranoid myself when it comes to tests, but I never cared enough if one antivirus has 10 and the other 5 labs points. There are plenty sources that show more detailed tests, which feel more trustworthy, since there are details. Indeed though knowing what the test tool does is something that would help us, not so much understand, but see results as even more trustworthy.

For better or worse, some malware do not hide only in virtual environments, but also are able to hide in the system and stay inactive, waiting for a chance when for whatever reason the antivirus will not be active and sneak up on the user.

All antivirus tools have some misses and quite some of them have a good killing ability. I am not sure if Avira is still one of the best, but that one and Bitdefender seem to prefer to hit more false positives, so they they will miss less viruses, rather than being more lax and miss more viruses.

Of course nowadays, at least to me that I am an experienced user, antiviruses all feel the same to me. [Commercial product reference removed as per site rules]

With that said though, Antiviruses are not anymore the perfect shield. Users should definitely use a browser addon to add a first wall of protection, be it like me an adblocker or any other addon, that can block malware and afar from that use occasionally an antimalware solution.

Although this is not the "Best Free Spyware And Adware Remover" list, I wonder why in the current one tools like RKill, TDSSKiller, AdwCleaner and Junkware Removal Tool are not mentioned, at least in a "products that are worth mentioning" list.

What privacy concerns might there be with free antivirus software? What are these companies getting from me by offering their "free" services?

For any software that connects to the internet (most of them do) there are privacy concerns involved. Hence each software has a privacy policy. It's a general misconception that, in return for the free products offered by developers they are selling your personal information. Most antiviruses that offers you a free product normally has a paid version, so their free version promotes their paid-for product, so that these satisfied consumers can think about buying them. 

But this is mostly not necessary for home users, because basic protection provided by freeware antivirus is well and good for them. Add together a couple of other free security products you are rock-solid. Others who doesn't offer a paid for service, has other sources of revenue. 

I have been repairing computer systems since 1989 and if there is one thing I have observed, the antivirus tests run in labs are significantly different than what happens to users' computers. Basing a choice of anti-virus upon the results of lab tests shows the media wants to avoid assuming any liability - they blame it on someone else. What good is advice where no liability was assumed? There are some informed comments here and I appreciate those who offer such responses. It is obvious because they are not concerned about themselves, they express concerns for all of us. KUDOS to them.

I've been using Bitdefender Free for about 6 months now and while I'm an advanced [cautious] user, I've had no issues with it. It took a while to get used to just leaving it alone, as in the past I'd go in and tweak all the settings of my commercial antivirus.
As the author wrote, there's no conclusive evidence that the Bitdefender Free engine is the same as the paid, but it's pretty likely. One area that the free is much better than the paid is in usage of system resources. This is likely due to all the supplemental features the paid versions have. At idle, the Free version uses about 25 MB of memory as opposed to close to 250 MB for the paid Bitdefender AV Plus 2015. Consequently, the paid Bitdefender uses as much memory as McAfee! But I digress.
My point is, the free Bitdefender is a great product for either A) a total set it and forget it user like an elderly relative; or B) a power user who has trust in the product and who'd be able to tell if something were not right on their system.

Here's the simple, layered security setup I use on my Dell (every day) laptop:
1) Bitdefender Free A/V - set & forget
2) Windows Firewall - set & f9rget
3) Mcafee Web Advisor (aka Site Advisor) - for supplemental URL blocking and search engine result ratings (Mcafee has the best product in this category IMO, by far - far better than Bitdefender "Traffic Light" )
4) Malwarebytes Free - manual scan every 2-3 weeks

Dates for the current Bitdefender Free filters/drivers:
avchv.sys System Driver BitDefender AntiVirus Active Virus Control Hypervisor driver BitDefender AVC 02/11/2012 13:17:46
avc3.sys System Driver Active Virus Control filter driver BitDefender AVC 17/04/2013 14:59:56
avckf.sys System Driver Active Virus Control Kernel Filtering driver BitDefender AVC 17/04/2013 14:59:58
gzflt.sys System Driver BitDefender Gonzales FileSystem Driver BitDefender Gonzales 22/04/2013 13:21:00
trufos.sys Dynamic Link Library Trufos Kernel Module BitDefender Antivirus 28/05/2013 12:12:19

I'd be very surprised if the Bitdefender paid versions used drivers as old as those.

Most of these are free for only personal use. Which of these are free for small businesses?

Comodo and Microsoft Security Essentials (limited) is free for Business use. Whereas Panda is free for non-profit organizations. 

Avoid Avast ads/popups/craps, etc...

Latest Stable Avast Free
Win 10 64

Win FW - Go to Advanced Settings - Top left side click "Outbound Rules" - Top right side click "New Rule" - Check that "Program" is selected - Click next - Check that "This program path" is selected & paste "C:\Program Files\AVAST Software\Avast\AvastUI.exe" without quotes - Click next - Check "Block the connection" is selected - Click next - Check all the "3" options are selected - Click next - Paste "AvastUI" without quotes in the option "Name" - Click finish.

Comodo FW - Set CFW to "Custom" - There will be couple popups - Check the popups description - There will be a popup for "AvastUI" - Select 'Remember This" & click "Block" on the popup for "AvastUI".

Win FW - I am running Win FW. And have blocked "AvastUI" as mentioned above.
Everything seems fine i.e Realtime/WebShield alerts, databases/streaming updates, hardened mode alerts, etc...

Comodo FW - I had blocked "AvastUI" as mentioned above. And ads/popups were not there. Forgot to check Avast functioning as mentioned above for Win FW. I think Avast should work fine.

Note - Only thing I noticed that Avast help links from the GUI mention "You are offline". So online content is not available & only offline content is available.

It seems blocking of AvastUI.exe as mentioned above takes care of all the Avast craps i.e no ads/popups, no upgrade button on the main GUI, no ads on the main GUI, no Chrome/Toolbar offers options during install/upgrade, etc...

I uninstalled Avast Free. But didn't remove the block rule for AvastUI.exe from Win FW.
I had a previous installer so installed Avast Free. No Chrome/Toolbar offers options during install. I then upgraded to the latest version & no Chrome/Toolbar offers options during upgrade.

of course the internet is now abuzz with the announcement from avg that it now collects and sells your info. so another product that i am done with. added to these:
Samsung spyware on tvs plus pups on phones
Lg spyware
Lenovo spyware and not safe chinese computers
Comodo adware
SOHO Routers
Seagate harddrives...come with rootkits

I do wish when posters tout something on here -- as in this recent post about "Moon Secure AV" -- they'd do more than tout but instead amplify their contribution, in this instance with some reference to calibre of performance and provenance of producer. Last I heard, Moon Secure was an Indian enterprise which used ClamAV and then ceased business. That's about as staggeringly unimpressive as it gets -- so why is this particular "AV" being promoted in this comments thread? Looks like spam to me.

The product has not been touted or promoted... simply suggested. There's a difference. Of course, we do remain open to suggestions. Any kind of over-promotion is always removed by moderators.

It's also worth mentioning that editor Panzer is responsible for posting literally hundreds of software suggestions on the site and we are very grateful for his contribution. MC - Site Manager.

MoonSecure Antivirus:

Not sure about listing MSE Microsoft Security Essentials as unsuitable or subpar.
It is true that they rank low on the test scores.
But there's an assertion that MSE focuses on the most popular exploits.
So we might have a "real-world" vs "academic" controversy here.
Ie in an academic settings (AV tests), with contrived threats, ie, including some rare ones, MSE doesnt perform well.
But in the real-world with threats that are commonly seen, it performs just as well as the others.
Ie you have no greater chance of becoming infected with MSE than with any other AV.
MSE is also free and fast, so I would not demote it.

My personal opinion, is if you take the AV Tests, and give them a good shake (ie replace the threats tested with an different but equivalent set), then everybody's going to score differently.
So my opinion pick a fast, unobtrusive one. That's MSE or BitDefender today, but every year brings a new mix.
Actually, before coming here today i would have put Panda on that list, but people here report popups.
And supplement with Malware Bytes anti-malware and Super Anti Spyware once a week.
And use Sandboxie or VMware player or VirtualBox for risky stuff.

You make a very good point johnvk, in fact several of the people I still service use MSE and none of them are getting infected. This is because they realize an antivirus solution is only part of the strategy for staying infection free. The rest depends on the user and how they operate their system when connected to the internet. If this usage is such they think they can surf blindly into any site and install software from any source, no matter which antivirus they have, infection is a matter of when not if. Common sense together with browser add-ons such as WOT and uBlock Origin plus Sandboxie, WinPatrol Free and in my case Toolwiz Time Freeze for software testing will be perfectly adequate when used with MSE. MC - Site Manager.

Panda Free Antivirus is a PUP on my Win 7 64-bit in that it keeps popping up an ad. for Panda Pro at random times and too often in the middle of something I am doing on the desktop.

> "Panda Free Antivirus is a PUP on my Win 7 64-bit in that it keeps popping up an ad. for Panda Pro at random times and too often in the middle of something I am doing on the desktop."

Then uninstall it and use something else. It is a free program. I see nothing wrong with providers of free stuff trying to get you to upgrade to something that gives them some compensation for teir work. If they do it in a way that is inttrusive to you, then just move on. Maybe buy a pay program = no ads (well, usually).