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  • Excellent malicious URL blocking, network protection, outdated software checking, integrated password manager, and comes with a rescue disk.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


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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)


Antivirus programs are designed to protect their users. Within this process there are always likely to be some false positives. Specific to your experience, I can't comment about Instandbird because I have no knowldge about how they operate but Sourceforge have recently introduced a wrapped installer (like cnet) which will certainly explain Bitdefenders intervention there. I always recommend users research what they want to install via Google first in case something is missed by their antivirus, in which case the above links would have provided the information necessary to make an informed decision. Genuine false positives can and should be reported to Bitdefender for the benefit of other users. MC - Site Manager.

Yes, what a shame that SourceForge decided to add a wrapper to their installers (and they use to be a completely reputable site...).

The free antivirus from BitDefender with real time protection has been around for quite sometime now. Although it seems good, but earlier, it did not come with much control, which many users saw as a disadvantage. Although, with recent versions, they have made a few changes to the product, as a result of the users feedback. We had a discussion on the product in the Freeware Forum. You can take a look:

Malwarebytes anti malware I think deserves some mention here, granted its not a dedicated antivirus but its malware scanning I feel is on par with Avira.

I use Avast and malwarebytes as both allow for manual updates, a rare feature. This combined feature gives me the good I would have got from avira, but avira got in the way of my gaming. Avast has silent gaming mode feature, allowing my games to move along without interruptions. Avast version 8 is lot more lighter and resource friendly.

Malwarebytes is featured on the appropriate pages of this site including these: As the free version contains no real time protection, it is not suitable for inclusion in this review. MC - Site Manager.

I posted a long time ago trying to find a way to (completely) avoid the (obnoxious) Avira nags and finally gave up and switched to Avast. I'll do a more scientific comparison soon, but pretty sure Avast uses the same amount of memory or less than Avira at least on my old pIII 512MB ram PC with XP pro (which is normally not as bad as you'd think for my needs, unless I have 400 tabs open in Firefox!)

I haven't had any infections with Avast (yet) albeit it has only been a few months, and went many years with zero infections with Avira. Although Avira worked well re protection for me, a couple of less tech-savvy clients DID get a couple of nasty infections (Trojans, one of which took down the whole system) with Avira running (albeit about 2 years ago)- so Avira is certainly not perfect re doing its job, of course, as I guess none of them are. (I have since placed these too-frequently infected clients on Limited User Accounts and so far no infections for them either...)

One thing I really like about Avast is a general software update feature like Secunia, which is a little less obtrusive and more user-friendly than Secunia, at least in my opinion, and combines AV and very important software updating alerts in one package.

For a long time, I used Avast on my old PC with same config as yours.. P-III with 512 MB RAM. It used to run really light. Firefox did make system a bit slow :)... but was manageable with less tabs.

yeah, something is wrong with my Firefox settings- it is now using 235MB of RAM with only 2 tabs open (and only a few basic addons like ABP)- tried every Mozilla "tip" and also Chrome and not much better, at least a while ago. Anyway, right now AvastSVC.exe is using only 1.8MB and AvastUI.exe is using only 1.7MB of memory. SVC jumps to around 10MB when a new tab is opened, as one might expect, but pretty sure Avira sat at approx. 10-20MB when idle, jumping when opening a tab or file. That said, even 20MB is nothing to most (newer) PCs- Firefox is my problem, the hog...but that's another forum...

Probably nothing wrong with your FF settings, simply that FF is a massive resource hog in my experience.

Yeah, I think you're right- can you suggest any alternatives for old PCs? NoScript seems to help, maybe, (and was it more or equally responsible for my zero infections in over 10 years than Avira?) but is kind of a pain and definitely not user-friendly enough for typical users- but it didn't help much. And Chrome was just as bad re hogging RAM with more than a few tabs (I tend to work with many), at least for me. The browser reviews I read gave the least use of RAM resource award to FF. With only a few tabs (less than 10-20) open (typically using FF, Office with big files, PDFXchange, and Thunderbird simultaneously), my PC is just as snappy and useful as much newer ones- so I hate to just trash it for both financial and ecological reasons. I'm changing my browsing habits by grouping tabs by "project" in bookmark folders and keeping only a few open at once- this brings my PC back to "snappy and happy" and is probably a more organized approach to working anyway...

I'm also going to try an SSD and also ReadyBoost- what the heck, why not? I can hear the HD toiling away when my tab number creeps up and FF jumps from RAM to "virtual memory" (i.e. the slow old mechanical HD), so this may solve the problem- will post results in a more appropriate thread..

Anyway, back to the topic, I will reinstall Avira and do a "scientific" test on memory use of Avira vs Avast (turning off one before testing the other of course) as soon as I get a chance...

I also changed to a SSD and it's MUCH faster, but I still do get slowdowns with most AV. Just been using Avast for the past 2 weeks and eventually had to remove it because of the impact on browsing speed - all browsers - FF22, IE9 and Seamonkey. I recommend you try Seamonkey as a FF alternative, I find it quicker. It's not as "modern" interface but it's faster and also many of the FF addons work on it, the engine is based on FF.

The comments are going off-topic, and I will request you gentlemen to take this discussion to the forum please. Any more comments on browsers will be deleted.

Huh? Please don't be so trigger-happy, I was mentioning the real impact of Avast upon browsing speed. I concluded that the least impact was with Seamonkey. I have no desire to discuss generic browser topics here, merely relay some of my experience of 20+ years to help others, if they need it.

My comment was not directed specifically towards yours, but to the whole discussion. Don't take it personally.

wuuuh? I, for one, greatly appreciate all the comments- very thoughtful and helpful. I think most people use their computers mostly for internet use and AVs are mostly to prevent damage during that use- so AVs and browsers are intimately related- how "good" a free AV is has very much to do with how fast you can browse with it on (however old or new the PC is)- so I don't think it is really much off-topic, if at all. It is very possible some browser/AV combinations work speedier than others, and that would be good info to know re the "best" free AV...

Also, I know you didn't mean it that way, but I found it a bit sexist to be called a "gentleman"- I am a woman.


Thanks for your post, LynVT.

As a long-time user of Avira Free A/V (on a dozen machines I tend to, XP through Win 7), I look forward to learning of your further experiences with Avast -- especially on older machines with limited resources (such as your P-III with 512 MB RAM).

To date, none of these machines has experienced a malware infection. (Avira's default settings were changed on every install, such as setting both heuristics to High, enabling every option under Additional Settings for the System Scanner, and selecting every threat category, except Unusual runtime compression, under the General tab. In addition, the Secunia PSI, WinPatrol and the COMODO Firewall are also installed.)

(For the record, the large nag screen pop-up has been successfully suppressed on every machine, though an occasional tweak is required after some major updates from Avira...)



Hi AJN- I did have all the Avira machines set to maximum heuristics- had it scan everything- checked all threat categories except games and jokes. Didn't have Secunia running when they got infected (do now), and these users would be too confused by WinPatrol or a firewall other than the XP one (which I did have on), so they were flying in the wild with just Avira and the XP firewall- clearly not enough. I also added WOT to their Firefox and explained to "only go to WOT green sites". So I'm not sure if it is the Limited User Accounts or WOT or Secunia (or all of them), but these users who previously picked up infections quite often, have been clean now for several years.

What method do you use to suppress Avira nags? The one I used to use that worked stopped working about a year ago. Thanks for your comments.

Hello LVT,

Just wanted to check to see whether you had received my reply to your question, which I sent through your contact form at Gizmo's site (the Admins, understandably, are not enamored of open discussions on how to violate the EULAs of software we list...); it was titled "Avira Pop-up Suppression" (though other security-related issues are also discussed) and posted on 2013.07.23, at about 1721 (U.S. PDT). If not, please let me know where I might forward it to you. Thanks.



Avira have updated their Free Antivirus to v13.0.0.3882; 102 MB (off-line installer), 2 MB (on-line) (2013.07.12) -- (As of this writing, Avira have yet to update their product's nomenclature at their site, though the version supplied is the current one.)

With this release they have eliminated the “Expert mode” from the Configuration panel (all options are now displayed as if this mode were always activated, saving one click and making the User Interface a tad cleaner); they have also included another cumulative roll-up.

Thanks for the heads up!

Neil Rubenking has a recent article in PC Magazine, "Microsoft Security Essentials and McAfee Fail Security Certification," discussing the Dennis Technology Labs real-world testing results for several anti-malware apps, including avast! Free Antivirus 7, AVG Anti-Virus FREE 2013 and Microsoft Security Essentials -- . (User comments at the bottom are also worth a look.)

It will be interesting to see if MSE fares any better in formal testing when its next version is released (v4.3.215.0 pre-release is available for download from Softpedia --

Another "warning", and I've tried Avast on and off for at least 10 years, is that it is surprisingly resource-heavy. The latest releases during web browsing are especially slow.

Really? Avast came out as the lightest antivirus among the 20 products that have been tested at Raymond Memory Usage Test to See Which is the Lightest Antivirus Software Although there is no CPU usage considered in the tests, I wouldn't be surprised even if it was low. Avast is a lightweight antivirus. I've no slow downs while browsing too, but if you feel there's any slowdown, you could disable streaming and reputation services. I have switched it on and my web browsing speed is normal.

In my experience looking at the CPU and memory usage under the Windows Task Manager, or at least the headline values shown there, is only part of the picture. Applications often also create extra svchost.exe files and it's not easy to determine actual application resource usage without a lot of digging around.

Web browsing is slow on my laptop using Avast and it was similar when I trialled a paid product which uses the Avast engine. I am now using 2 other paid products with very high security levels but very light on browsing impact and overall system impact. I cannot name them due to the policy of this forum.

When I tried Avast for Android on a Samsung tablet it worked fine with no noticeable browsing or other issues. The issues on my laptop were repeated on other windows machines.

I have been using Avast on my system for years now, and I can say that it runs very light. I have used it on XP previously, and now am running it on a Windows 8 PC. Even with the web shield on, it runs very light, and does not slow down the computer, or the browsing in anyway. I have also installed it on other systems too, of my friends and relatives, and in their PCs too, it runs light, and without slowing the system. I think you should look at other factors on your system, like other security software that you might be using along with Avast.

I don't run any other security software in realtime. The only things I can potentially think of may be old AVs perhaps not fully cleared out despite using uninstall tools and CC registry cleaner. However, it was the same browsing problem with Avast and Gdata and I understand that Gdata uses the Avast engine. Anyway, it's removed and I have decided to revert on my main machine to Comodo AV.

Hi JonathanT, Can you please share your views on Bitdefender free and Immunet free with me. i want to know how good they are. thanks :)
BitDefender free is an on-demand AV. I haven't been keeping up with Immunet lately but afaik it's detection rates are subpar - MC might know more about this! Again I'd recommend just sticking to the tried and tested software listed here. :)
Bitdefender free is now a completely different program including real time protection. When it was first released it was quite restricted regarding settings but in response to user feedback this has now been improved. The test results quoted on their site are somewhat misleading because they refer to the commercial edition and it is not clear exactly which components (and how much of them :)) are contained in the free version. "Some of these technologies, also common with our main product line, have allowed Bitdefender to outpass major competitors such as AVG, Avast or Avira". If though the only items missing are components like Safepay and the AV engine, signatures and heuristic capabilities are the same then this would be more than adequate for general home use. MC - Site Manager.

It appears that Bitdefender may have now removed their free program. Even clicking the "Free Antivirus" link at the bottom right side of their main page does not such thing, unless it's a temporary glitch.