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.

Read more about Antivirus Engine and other related details at the end of this article.


Rated Products

Kaspersky Free Antivirus/ Kaspersky Security Cloud  

The paid security giant forays into free category and outsmarts its rivals

Our Rating: 
License: Free (Limited features)
  • Similar signatures & cloud features as its paid counterparts
  • Performance impact is decent on higher end systems
  • Strong behavioral blocker
  • Attractive GUI with no ads
  • Top-notch detection and always up-to-date
  • Thorough malware removal and disinfection process
  • Privacy policy (complies with GDPR)
  • Default settings cover most users
  • Bundles with Kaspersky VPN (can be uninstalled)
  • Fairly good web protection
  • Powerful exclusion settings (even for specific modules)
  • Extensive scan logs
  • Protection settings are locked with presets in Kaspersky Free Antivirus (KFA) [is available in Kaspersky Security Cloud]
  • Long but thorough system scans
  • Performance hit becomes worse on lower end systems
  • Slow update installation
Read full review...

Avast Free Antivirus  

The only antivirus with a fully customizable installer and selection of user preference components.

Our Rating: 
License: Free (Limited features)
  • 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  • Excellent malicious URL blocking, network protection, outdated software checking, integrated password manager, and comes with a rescue disk.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
  • 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
  • Offers Google Chrome and various bloated secondary components during install [Choose custom install]
Read full review...

Comodo Internet Security Premium  

Provides a multi-layered protection scheme with HIPS, sandbox, antivirus and firewall.

Our Rating: 
License: Free (Limited features)
  • 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
  • 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.
  • Chromodo browser, Yahoo search engine, custom DNS and Geek Buddy offered during default install. [Click customize installation during install]
Read full review...

Qihoo 360 Total Security  

This free antivirus is better than most commercial ones.

Our Rating: 
License: Free
  • 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
  • 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
Read full review...

Avira Free Antivirus  

A free antivirus with high quality signatures, very fast updates and less false positives.

Our Rating: 
License: Free (Private/Educational use)
  • 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
  • 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
Read full review...

Panda Free Antivirus  

Gives you antivirus protection with low memory and CPU usage, and collective intelligence cloud security.

Our Rating: 
License: Free (Private/Educational use)
  • 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
  • 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
  • Watch out for Panda security toolbar during install
Read full review...

Honorable Mention


Related Products and Links

How to make an antivirus engine

Other Articles By Chiron

Related Free Antivirus Software Articles

Related Security Articles


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.



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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Please rate this article: 

Your rating: None
Average: 4.3 (2219 votes)


Although it is not as good an antivirus system as these above, MSE does have the advantage that it can run on slow machines without draining the power too much. It also has no legal issues about commercial or non commercial use. For these reasons for many people, it is actually a better solution.
Check here, and you'll see that Avast is the lightest antivirus using least memory resources. The way it flushes/resets the memory after every 10sec is an innovative feature to keep memory usage under check. I admit that the results doesn't take into account the processor usage.
If you check the results for MSE, you will find that it consistently scores near the bottom. Thus, it does not offer sufficient protection for me to recommend it in this review. For users who find the other antivirus products in this review too resource intensive, I would recommend that they try Panda Free. It should be quite fast, even on slow machines. As per legal issues, Comodo Antivirus is free for commercial use, although if the company has many computers they may wish to consider Comodo Endpoint Security, which is paid. That said, there is still a free product recommended in this review which also works for commercial environments. Everything taken into account, I do not think that it is a good idea to recommend MSE. It just doesn't provide the level of protection which people deserve. Thanks.
Hello, I've just completed a major revision of this article. Therefore, if anything seems wrong, such as a link is not working or the wording is unclear, please let me know. This is still a work in progress, but I wanted to provide you with my new ideas, and testing criteria, now rather than later. Please let me know what you think of the new review. Your feedback is much appreciated, and will be very helpful. Thank you.
Yes. If users have trouble uninstalling Avast, or experience other problems after uninstalling it and then reinstalling it, this uninstall utility is very helpful.

In hopes of hardening my older XP Pro lap top before the SHTF event in April, I loaded up Avast and was initially satisfied with how it did it's job. Then I reached a 30 day anniversary and the constant nags started. Now I have no working anti-virus and I am also unable to remove Avast or disable it's constant nag pop ups. As of this date I would rather be scalded than pay the Avast pirates a penny for their miserable product.
Anyone looking for free anti-virus I would advise stay well clear of this nasty, intrusive, offering.

As sicknero mentioned, did you register the product? Regardless, it should still be able to be removed (and if it can't this sounds like a bug), but the reason it's nagging could very well be because of the required registration. Thanks.

The free version of Avast requires that you register with them to use it for more than 30 days.

I'm guessing that you didn't do that?

What about Qihu 360 Internet Security?

Only products with a proven history over a long period outside of their domestic environment are likely to be considered for this review. MC - Site Manager.

Have been testing AVG, Avast! & Avira. So my 2 cents, for what its worth:

1. Whilst AVG certainly is very capable and suitable for the vast majority of users, it does tend to be a bit "heavy" and slow, but all round a solid product.

2. Avast! may well be rated highly, BUT be warned.... its a bandwidth hog, doing all sorts of strange things in the background. At first I thought it was a bug or something weird going on... but a quick search on Google shows that this is well known. If you are using 3G or any form of controlled bandwidth, suggest you leave Avast! well alone! Setting to a minimum file only protection did not seem to help the situation either.

3. Avira.... have since 2013 removed their intrusive ads (This needs to be updated in the above summary). I currently use this Anti-Virus, and have no issues so far!

I have removed the warning about Avira from the article. Apparently they now provide free users access to their cloud as well. I have updated the article to mention this as well. As for the other products, I will be updating this article (once I have more time) to better differentiate between the real-world protection offered by the various products. To do this I will draw on the results from several testing agencies. However, I am very busy right now and not sure when I'll find enough time for a drastic rewrite and research which this necessitates. That said, it will happen eventually. I was not aware of the issues which Avast causes on systems with slow internet. I assume that is likely caused by cloud-based activities. Has anyone else run into a lot of problems with Avast hogging the band-width? If so I'll update the article to warn about that. Thank you.

Avira Free Antivirus has been updated to version (2014.03.04; 132 MB).

(Again, the update nag screen has been eliminated.)

Thank you for bringing this to my attention. I have now edited the information in the article. Let me know if you still see any issues. Thanks.

You're most welcome, Chiron (and thanks for updating the Avira description!).

Incidentally, Avira have added two additional enhancements by incorporating their "Protection Cloud" and "Browser Safety" features in their free A-V - (it will be interesting to see what effects this might have on future testing results...).


P.S. In case you don't follow his articles, Neil Rubenking, Lead Analyst for Security over at PC Magazine, does his own extensive in-house testing (along with relying on results from the various testing labs); his most recent overview of free anti-malware solutions (2014.01.08) can be found at,2817,2388652,00.asp . (Should you ever wish to contact him, Mr. Rubenking is very gracious about answering emails.)

Thanks. I've now added that it also includes the cloud. However, I did not see any indication that the new browser safety addition is yet included. It seems to be in Beta. Thus, I did not add that to the article yet. As for updating this article to better compare the products, I am still trying to find the time to do that. I have been very busy lately, but do still plan to update this article such that it will better differentiate between the real-world protection offered by these various products. At that time I'll be using the results from multiple testing agencies. Thank you.


I should say online activation is "optional".


I agree with George.J. Although it will run fine for 30 days without registration, it will stop running after that time runs out. Therefore, that is why I say that it requires registration. If you have any questions about that please feel free to ask. Thanks.
Avast will run free only for 30 days unless you've activated it. Upon activation you get a 365 day license.

Avast! Free Antivirus was updated to version 9.0.2013 (86 MB) on 2014.01.23.

Thanks for letting me know about this. I have now updated the information in the article.

I am using Bitdefender, due to all the excellent reviews of their product. I did have a problem with Ccleaner locking up my system whenever I did a scan.
According to the forums on Bitdefender, to avoid this problem, all you have to do is turn off the virus shield on Bitdefender, whenever you run a scan with Ccleaner. Since I started turning off the virus shield, to run Ccleaner, I have not had any problems. Just make sure you turn it back on when you finish cleaning with Ccleaner. I love this anti virus, and I do not mind a little extra work, to keep it on my computer. I wrote this as a help to those that maybe having the same conflict with Ccleaner. I hope I was of some help with this issue.

That's a very strange issue. I hope it's already been reported as a bug on Bitdefender's forum and will be fixed in subsequent updates. That said, I'm glad to hear of the workaround, and will let others know if I hear of anyone running into the same problem. Thanks.


The conflict between Bitdefender Free Edition and Ccleaner, has not been fixed. I am still having the problem. From what I understand, Bitdefender has no plans to resolve the issue.They say that it would put the computers that their product is protecting at risk, to resolve the problem. I was told by Bitdefender to do the work around, of turning off the Virus Shield, when cleaning with Ccleaner, or to delete one or the other. Bitdefender is a little arrogant, when it comes to their product. I don't blame them for that. I think they have a very strong product. So if they think that resolving the problem would put my computer at risk, then I have to agree with them to not resolve the issue. Both Bitdefender and Ccleaner are great products to have on your computer. So I have chosen to do the work around.

Thank you for updating us about this. I'm really not an expert in how products are coded and thus will not argue with them about this. However, it does seem strange that other products do not have the same issues. Either way, I suppose it's a relatively minor issue for a good free AV. Also, for anyone else reading this, if the issue is bothering you too much you can also switch to one of the other great AV's in this article. Thanks again.

I've noticed a few issues with Avast lately that have caused me to jump ship back to Avira (whose major downside of annoying nag screens I can mitigate).

Issue number 1 has something to do with startup protection. Basically I can't mess with my startup entries with any of my centralized tools, like CCleaner.

Issue number 2: It recently had an annoying false-positive with my VoIP client ( RaidCall ), and then proceeded to not let me whitelist the program without going on the internet, doing research, and changing the settings on ENTIRELY too many things, instead of simply letting me say "Your last detection was a false positive".

The first one I was willing to work around until Avast updated to fix the issue, which might have taken many months (not that big of a deal. I check my startup entries once or twice a month). The second one cuts me off from effective performance in my cooperative games (group coordination is much more difficult without VoIP). That I'm not putting up with for even a week, because it's an implementation flaw as far as I'm concerned. False positives happen, and without a simple/easy way to unblock/undo those, this program is a loaded handgun being waved around by someone that isn't quite stable. What happens if it gets a false-positive on Windows Explorer next (probably signature/hash based whitelist for important OS files... but still, I'm not dealing with it), or maybe my browsers get targeted?

Both Avast and Avira are very good choices. As for the startup protection, I was not aware of that, but I suppose the upside is that malware likely couldn't mess with the startup entries easily either. However, for a user desiring granular control I understand the issue. As for the false positive issue, all AV's will sometimes have false positives. Sadly, with the vast amount of malware out there this sort of aggressive signature is necessary. Thus, please report false positives using the information I have gathered in my other article here: All AV's have had false positives in the past, sometimes with important files. This is sadly unavoidable. However, the AV companies themselves are also aware of this problem, and are constantly doing everything they can do to try and ensure that the important files are whitelisted, and will thus be excluded from detection. Thank you.

Larry Seltzer of ZDNET has an article some may find useful, "Antivirus on Windows 8/8.1 compared" - (2014.01.21), which references the new test results from AV-Test (

Though mostly discussing paid applications, a few consumer freeware are mentioned (and yes, Microsoft Windows Defender 4.3 was dead last).

Thank you very much for this link. I will take a look at this when revising the advice in this article. Also, AV-Test is one of the testing companies whose results I will be drawing on to compare the products. Thanks.