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  • Excellent malicious URL blocking, network protection, outdated software checking, integrated password manager, and comes with a rescue disk.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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Average: 4.3 (2219 votes)


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.

Please let people know that BitDefender is no longer compatible with Windows7.


This is not true. MC - Site Manager. "Operating system: Windows XP SP3 32-bit, Windows Vista (SP2), Microsoft Windows 7 (SP1), Microsoft Windows 8. RAM: 512MB. Hard disk space: 700 MB".

Reluctantly I've just abandoned Comodo AV after yet another nightmare install attempt (in fact, many attempts!). Version 7 worked fine but version 8 wont install despite following Chiron's clean install guide on the Comodo forums to the letter - Comodo keeps on saying it can't load because Avast is incompatible despite me looking everywhere and, as far as I know, removing everything to do with Avast. I also used the firewall part of CIS and I particularly liked the way you could bind applications with Comodo, for instance, to a VPN to safeguard against disconnects.

Anyway I've switched to Panda free AV and working nicely - never used it before and wasn't aware of its excellent performance in recent AV tests.

It is important to understand this is not Comodo's fault, but that of Avast! and I have encountered similar "after Avast!" issues with other security programs, especially when the Avast! uninstall tool provided by the vendor has not been used. MC - Site Manager.

Yes, I completely agree. The problem is very much with Avast, and having used both their removal tools and searched manually for any remnants, I and the avast community have run out of ideas.

PS - I hope it didn't seem as if I was blaming Chiron or the excellent work he does both here and on the Comodo forums.

One of the things I love about this site is that the reviews are always reviewed, meaning that when things change, you often update the best-of lists. And the comments are often very helpful.

Just out of curiosity, though, wasn't Microsoft Security Essentials top rated a while back? O_O But now it's off the list and just mentioned as sub-par? OHMY! What happened?

Also, an update of Avast gave be blue screens of death, and when I uninstalled it and tried to go to Comodo, it said I already had it and couldn't upgrade directly. I'm thinking it's because I have the firewall version. I reinstalled Avast but chose the minimal bells and whistles. So far - so good, but I'm thinking of uninstalling the Comodo firewall and trying Comodo anti-virus again.

Anyway, again what happened to MS Essentials?

I have been using Panda Cloud free for a few weeks and am generally pleased. However, it can use a lot of memory at times...Just my system or have others here experienced this?

http [ COLON ]//avlab [ DOT ] pl/sites/default/files/files/performance_test_november_2014.pdf Performance Test at AVLabs - November 2014 Probably the most complete performance test for antivirus suites I've seen around the web. It compares the performance of both free and paid solutions [and all of them].
Very interesting. It is useful to see idle resource loading but the performance testing is limited to trivial activities. It would have been nice to see performance statistics while performing less trivial functions including web browsing, downloading, and quarantining/removing actual threats.

I tried 360 for the first time this week, and I'm really liking it.

Unusually for a "suite" I'm actually finding all of the different modules useful as well.

It took me a little while to realise that activating the Avira and Bitdefender modules seems to be a two-step process. I ticked boxes that I thought had activated them and only later found other activation switches in the actual scan dialogue.

It is a little bit buggy I think ... some of the pop-up notices appear a bit erratic as to whether they decide to show themselves or not and it also seems to fall prey to the common W7 issue of disappearing systray icons. Installing it into a clean W7 seems to have helped with that though for now.

Some of it is a little confusing to a first-time user ... for instance I ran the Cleanup module which broke ClassicShell for me, until I realised that it had quarantined the toolbar components of ClassicShell.

All in all I like it a lot though, especially the alternative Windows updater. It seems to run happily with Comodo Firewall too and performance is still good even on my elderly 2Ghz/2Gb desktop machine.

By the way Chiron, your Dennis Technology link goes to the 2013 test results.

Thanks for a great article anyway. I've been using Comodo CIS for a couple of years or so now but I was finding that the AV component was a bit demanding on my low-end hardware, so this week I've tried out most of the alternatives on this page.

Panda I liked quite a lot ... I've used their portable on-demand scanner for a while now so I thought their free AV would probably be pretty good. Which it is, although for me it lacked some configurability and I didn't really like the auto-quarantine behaviour either. I tried 360 just out of interest really but I think I'll stick with it for a while. I seem to recall some concern about their privacy practises a while back but I've not heard that mentioned since.

I noticed this week that none of these AVs seem to flag the Nirsoft suite as malware ... I don't know if this is due to Nirsoft finally getting the message through, or some other factor such as heuristic scanning.

I'll still be using Emsisoft and MBAM as on-demand scanners as these two between them seem to pick up everything.

I see by the by the way that Comodo has received its first update in some time. I really happy to find that the awful process of unblocking blocked executables and adding them to the trusted list has been changed and is much easier now. But again, a bit erratic ... some blocked files can now be trusted via a small screen pop-up, while others still require the tedious process of opening the main program and adding to trusted, etc etc. I noticed also that some execs continue to run even though they get added to the "unknown" list and I have everything set to "block".

I see the settings dialogue has changed too though, so maybe there's something there which might explain that.

Thank you for your detailed response. It was very helpful. I've updated the link for Dennis Technology Labs. I also added a note about the auto-quarantine in Panda. As for Comodo Firewall, in case you weren't aware, a new version has been released to the Comodo forums. It can be downloaded from here: Please let me know if you have any questions, or if you find out anything else. Thanks.

Just a quick update ... the issue I mentioned whereby some processes triggered a "do not block again" dialogue while others have to be added to the list manually.

It seeme that this is related to system resources, so that when the machine is working hard the dialogue will take a long long time to appear.

Chiron, I installed Comodo Antivirus on my laptop with Windows 7. I plugged in a pen drive containing my software collection. Comodo detected some files as suspicious. I chose the option to ignore and add to exclusions, but this does not seem to work. Even choosing ignore once did not seem to work. It just kept on popping until I chose the option to either quarantine the file, or report it as false positive. How do I solve this problem? It's quite annoying.
Sadly, this sounds like a bug to me. I do know that ignore once does not work correctly (even though it was reported long ago by me). However, I was not aware that exclusions does not work correctly for removable drives (which is what this sounds like). If you are able, it would be very helpful if you could make a bug report for this on the Comodo forums. However, as a workaround, I would say that if reporting it as a false positive allowed it to work correctly, perhaps that is the best option for the time being. Thank you.
I too had the same thought, that this might be a bug related to the file being on a flash drive. I don't think I will be posting about it on the Comodo forum, as I do not intend to use the software for long. Strange that not anyone else has found out about this bug yet.

Most of antivirus programs have this problem (well, I know for Bitdefender and I think Symantec also). My workaround is to temp. disable on access protection.

Exclusion would not be very smart option with removable drive, IMO.

I am using [edited] for antivirus. Is that a good version, or does it have weaknesses? What other malware product would work good with it. I use Windows 8.1 platform.

Please do not post about commercial antivirus here. This is a freeware site, and we allow discussion of only free software. If you have queries about any of the free software, you are welcome to post. But, if you want to post about commercial software, you will have to look elsewhere on the internet.

Personally I don't use any AV on all of my machines recently and I feel pretty comfortable! No single issue for a very long period of time. As I have said many times - the use of AV software is too much overrated nowadays, especially if you are an experienced user. Moreover (just like with the cars) - I'm a big fan of performance, not of the security. There's not such a thing like "AV light on resources" - they all have impact on your system, always!...

Cheers everybody! :-D

There are some AV light on resources; I'm using Panda free Antivirus and I'm impressed by its very low usage of RAM and CPU. In this moment this is the RAM used by Panda on my PC:
PSUAmain.exe: < 1Mb
PSUAservice.exe: < 1Mb
PSANHost.exe: 11 Mb
AgentSvc.exe: 9 Mb