Best Free Antivirus Software


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To begin with let me say this: there is no best antivirus out there. Why do I say this? Any product that you take will behave differently against various virus samples since the AV engines and other components incorporated in them are of different technologies.

While one product might have higher detection ratio, another might have better malicious URL blocking or virtualization techniques, yet another might have lesser impact on system performance and so on.

Antivirus Engine:

It is used for Real Time malware protection of files and is the core component to scan data on your PC for detecting and removing malware from hard disk, memory, boot sectors, network drives, removable disks, or from external network traffic (internet).

  • How does an antivirus detect malware:

Firstly you got the signature-based detection which contains an offline database of known patterns of malware downloaded from the internet which can identify specific malware codes or family of malware. Then you have heuristic based detection that identifies pieces of code that are unlikely to be found in legitimate programs and hence is prone to false positives depending on the sensitivity of heuristics. Virtualization and sandboxing unpacks or executes unknown programs in an isolated secure environment so that their behaviour can be analysed and scanned using the antivirus engine. The latest one is cloud based detection that requires a reliable internet connection and sends the suspicious scanned file over the internet and the analysis is done by the vendors' machine running the cloud engine.

  • Scanning for viruses:

Most antiviruses include these basic scan types: On-demand scan/manual scan is initiated by the user from right click context menu or from within the software. On-access scan is initiated when the resource is being accessed like running an executable, copying files from external drives etc. Scheduled scan periodically ensures that the system is free from malware by setting the time and frequency for scanning. Startup scan/quick scan checks most important locations like running processes, startup items, system memory and services, boot sectors and so on.

To be Continued in the next update....... Firewall, Proactive protection, Web protection components and more.

Honorable Mention:


Discussion And Comparison

1. Qihoo 360 Total Security

The Good:

  • Totally free, light on resources, extremely fast scan times and pre-configuration protection modes
  • Smooth running installer with no adware, pleasing UI and comes with many themes
  • Fast updates/fixes and excellent customer service with immediate replies
  • Great signatures with multiple engines and in-house cloud protection
  • Web protection addon, browsing locking, webcam, sandbox and usb protection modules
  • Online shopping protection, malicious URL protection and network threat blocking
  • Includes Glasswire Firewall and Windows patch-up components 
  • Great detection rates, with very high zero day protection
The Bad:
  • Speedup and clean-up tools might not be for everyone (not present in Essentials version)
  • Bitdefender or Avira engines not enabled by default 
  • Might encounter few false positives
  • PUP [Potentially Unwanted Programs] detection needs to improve
The Ugly: 
  • Nothing for the moment
The Truth: Rating 10 of 10 5/5 stars
 Home |  Download |  v8.2 |  bit version |  Fully freeware |  41.6MB |  Win XP-10, Mac OSX

2. Avast Free Antivirus

The Good:

  • Extremely light on the system with a modern and clean UI
  • The only antivirus with a fully customizable installer, selection of user preference components
  • Works best in hardened or lock-down mode, which blocks all unknown programs (medium-expert users only)
  • Top notch detection capability, many secondary components to offer variety to a wholesome software
  • Excellent malicious URL blocking, network protection, outdated software checking, integrated password manager, and comes with a rescue disk.
  • Deep screen technology that includes Sandbox and Safe machine components for protection
The Bad:
  • Bloated default setup, some ads and pop'ups
  • Account creation for further protection after a month
  • Lack of an anti-ransomware module, and Deepscreen disabled by default
  • Cloud reputation, Malware signatures and HIPS module needs improvement
The Ugly:
  • Offers Google Chrome and various bloated secondary components during install [Choose custom install]
The Truth: Rating 9 of 10 4.5/5 stars
 Home |  Download |  v11.1 |  bit version |  Feature limited freeware |  193 MB |  Win XP-10, Mac OSX

3. Comodo Internet Security Premium

The Good: 

  • Feature-rich with lots of options for customization along with setting tolerance against prompts
  • Tweaked settings gives the best 0-day protection among the pack
  • Multi-layered protection scheme with HIPS, Sandbox, Antivirus and Firewall
  • Industry grade firewall with options for learning and behavioural blocker
  • Low on resources with various graphical skins available and a clean user interface
The Bad: 
  • Painful for beginners to use it, not very newbie friendly 
  • Av-module is a bit weak especially the signature based detection
  • Auto-sandboxing happens for various legitimate files, troubles with FPS games
  • Too many tweaks needed for better protection
  • Buggy software and updates are released slow.
The Ugly: 
  • Chromodo browser, Yahoo search engine, custom DNS and Geek Buddy offered during default install. [Click customize installation during install]
The Truth: Rating 9 of 10 4.5/5 stars
 Home |  Download |  v8.2 |  bit version |  Unrestricted freeware |  208 MB |  Win XP-10, Linux, Mac OSX

4. AVIRA Free Antivirus

The Good:

  • Pretty light on the system and runs smooth without system slow-downs
  • Clean ad-free GUI, Ad-free installer, No pop-ups or ads
  • High quality signatures, very fast updates, excellent detection on non-zero day threats
  • Deep file scans with very less false positives
  • Avira Protection Cloud makes for an excellent cloud engine
  • Browser safety Add-ons available for major browsers
The Bad: 
  • Zero day protection (heuristic & behavioural shield) is very weak. 
  • Ineffective Browser launcher which is a memory hog (can be uninstalled)
  • Painful removal for detected files. Repeated scans from Luke Filewalker increases CPU & RAM usage. 
  • Multiple file exceptions needs to be added (real-time and on-demand)
  • No firewall/sandboxing/web shield technologies
The Ugly: 
  • Nothing for the moment
The Truth: Rating 8 of 10 4/5 stars
 Home |  Download |  v15.0 |  bit version |  Free for private use |  200 MB |  Win XP-10, Mac OSX

5. Panda Free Antivirus

The Good:

  • Low memory & CPU usage thanks to cloud protection 
  • Tiled UI with customizable interface and nicely rendered Settings interface
  • Collective intelligence cloud security - Downloading virus definitions is history
  • Good detection rates and behavioural analysis program
  • Fairly good web protection and hardware resource handling

The Bad: 

  • Dependant on internet connection leading to weaker offline protection
  • Slow scanning speed, no fingerprinting (successive re-testing same files) and at times issues with virus removal
  • Not really light, performance impact in web browsing, installation and copying
  • Certain false positives despite the information available at cloud

The Ugly: 

  • Watch out for Panda security toolbar during install
The Truth: Rating 8 of 10 4/5 stars
 Home |  Download |  v16.1.1 |  bit version |  Free for private use |  61.4 MB |  Win XP

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I have no link to give you. I read it in a Magazine, and I do not remember off the top of my head what the name of that magazine was. It is not my intention to be trolling, Please feel free to delete my comments. If I find that magazine in the future, then I will be back to give you that info. Have a GREAT DAY sir !!

Not many AV scanners do detect OC inside installers.

For instance the FreeFileSync installer, which runs the Open Candy exec OCSetupHlp.dll, is passed by most of the major AV providers. Malwarebytes flags it as a PUP.


I clicked on your link, and if virus total is saying that Bitdefender does not detect OpenCandy, then that is just wrong! I had to update PDF Foxit Reader yesterday, and it comes with OpenCandy. My Bitdefender Free Edition did detect OpenCandy yesterday !! Then I proceeded to remove it from my system.


If you read my comments all the way through, then you will see that I have a bigger problem than just with AVG not detecting OpenCandy. I think that all the antiviruses in this list do detect OpenCandy in one form or the other.I am sure there are several out there that do not detect OpenCandy at all. In my opinion that is a mistake. At least detect it as a PUP.

Thank you for your response !!


So far i used and recommends/install Comodo Internet Security to my neighborhood. Though comodo antivirus never had a chance to be in any top 10 best antivirus reviews in my experience my system is stable so far and can be commercially used that does not required activation. My downside is i never used my pc like i dont care..?! Like i dont go to any site that has bad ratings on it or i feel that a site is a bad site or a link is a bad link - I dont download and open any file which is unknown to me. Bad thing is that few people does that. It was confirmed to me when i recommends it to a company and they installed it to hundreds of computers - they say most of their users dont really care what they click because they know someone will fix it.

I wanted to tried avast and bitdefender but it does required registration and activation - and it is a bad thing for offline users. They should remove registration and activation. And should be a standard for any free software.

Thank you for your feedback. My problem with most of the antivirus reviews is that they tend to put most of the emphasis, in one way or another, on detection of threats. However, I am of the opinion that for a user in the real world what really matters is whether the computer was protected from infection or not, regardless of how it was protected. As for Avast and Bitdefender, I do understand what you mean about activation. However, hopefully there is a way you can connect your computer to the internet for the small time required for activation. Still, I agree it would be best if they could keep track of users in some other, less intrusive, manner. Let me know if you have any other questions. Thank you.


I have looked through you sources as follows :



Dennis Technology Labs

What I found was, is that Comodo Antivirus was not presented as a stand alone product, but as a suite. I only found three from your list of antiviruses, that presented their antivirus as a stand alone product. As per this link :

I have seen testing of antivirus programs, that tested much better within a suite, than as a stand alone product. Do you have any test results of Comodo Antivirus as a stand alone product?

Otherwise I will have to go with one of the other three that were tested as a stand alone product. At this point, I do not see how Comodo Antivirus stands as the best, when I can not find their Antivirus, tested as a stand alone product.

For the record Comodo Internet Security Premium is also freeware.

George J,

Thank you for your reply.
I am aware of that.
Thanks !!

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...