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  • Excellent malicious URL blocking, network protection, outdated software checking, integrated password manager, and comes with a rescue disk.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


I'm sorry, I just noticed this reply. As far as I know Avast is the only one in this list which requires registration. However, please note that I have not tried out all of these on my system, and thus cannot be entirely sure. If you find that any of the other programs in this article do require registration please let me know and I will include that information in the article. Thank you.

I too intensely dislike the newer Avast. I used to work really well, but starting this year (even though they said they still supported Windows XP) every attempted update crashes and will not complete. Secondly, it is constantly trying to change my search page to Bing or Yahoo will and not allow my current Google. I have read complaints from others who state that once having allowed the changes they cannot be undone. Point 3, the newest update has severely slowed my ability to use the internet and even do anything locally on my machine (once I uninstalled Avast, everything returned to usual).
I will no longer use Avast! Especially since the recommend Yahoo and not Google. I no longer use Yahoo because of spam issues.

"Bitdefender Antivirus Free Edition" has a serious problem, I tested it on three different computers running Windows 7 x64, and on each one the program/installer was in Romanian and the option to change the language was greyed out, this issue has been there ever since it came out and I never managed to find a solution for it.

Also, I'd like to know your thoughts on "ZoneAlarm® Free Antivirus + Firewall 2015" I've used it in the past and my experience with it was quite positive.

That's a strange problem to have with Bitdefender Antivirus Free Edition. If you don't mind me asking, where did you download the installer from? As for ZoneAlarm® Free Antivirus + Firewall, sadly it's not suitable for this article as it's more of an Internet Security Software than a straightforward antivirus program. This is a distinction we make with this article because all of these software must be able to run with a firewall of the users choice. For the article on the Best Free Internet Security Suite (which includes ZoneAlarm) please see here: Thank you.

I always download it from Bitdefender's official website:

Thanks for pointing that out, I will check the other article.

One more thing, I'm curious as to why "MSE" isn't included in that list? From my experience it's an excellent set-and-forget antivirus and correct me if I'm wrong but I believe it has been integrated in Windows 8 and higher.

That's strange. Is it possible that it is detecting the language of the systems you are installing it to? What is the set language of the OS you are installing to? Also, if anyone else has experienced this same issue with Bitdefender Free please respond and let me know. Thanks.

Not possible, all three computers I tested this issue on they are in English.

I also just tested right now on my own laptop (running Windows 8.1 x64) and I'm having the exact same issue.

Screenshot (before):

However I managed to find a workaround for this issue here:

Screenshot (after):

Thank you very much for the digging. I was unaware of this problem. However, I have now added a link to the post you discovered to the article. I'm sure this will help many others who otherwise would not have been able to use this quality software. Thanks again.

I tried it today briefly but it was disappointing. During the initial scan it stated that it found and cleaned 16 infected files which is highly unlikley considering the semi-empty PC I was testing it on, but even when I opened its log, it was empty. Also, the fact it has no options to speak of leaves a lot to be desired.

Indeed, I wanted to try it several times but was unable to due to that problem.
In any case, I'm glad I could help.

Real World Protection Tests at AV-Comparitives... Panda scores 100% at the expense of too many false positives (34). Good results for Qihoo, AVG(IS) and Avira(Pro).
Take a look at Tiranium Internet Security. A splendid antivirus with firewall. Seems to be getting rave reviews.. Certain community video review tests Review 1 Comparitive review 2 Review 3 If you aren't interested there's also a Cloud Scanner that you can work with your current antivirus and a KeyLogger provided by the developers
As MidnightCowboy said, at this time it is not a good fit for this article. However, I will keep an eye on it and see if it continues to improve, including testing by independent testing agencies. Thanks.
An emotional Paste from DubSeven the developer, and the reactions Tiranium will be closed in a month.
One great comment. "I saw how everything depends on money. The computer security is no longer about security but about money". You could pretty much extend the first part to everything on the planet. MC - Site Manager.
I guess you meant 'planet'. I'm surprised that the developer is an 18 year old kid, and was 13 when he first coded Tiranium. Those insults must have hit hard on him. But he did some great work at such a young age.
Indeed. The trolls enjoy their work however and must be really pleased with the result. Some might even suggest that one or more of the established names in the industry might have been involved. It's well known that some vendors employ legions of fanboys and trolls to post good and bad "reviews" online about competing products. Thanks for spotting my typo above which is now corrected. :) MC - Site Manager.
Tiranium is an interesting project but is just a one man show with a small team of "helpers". We won't be featuring this here (or anything else like it) unless it develops a lot further and begins participating in recognized independent tests. MC - Site Manager.

Well, I tried it, I'm sure it's a wonderful program, BUT, even after a careful installation, it nags the devil out of you to sign up for the stuff you didn't want. Have been using Bitdefender for a year, no problems. Before that, was using Avast, my favorite, but Avast changed something in their detection rules and it would not allow me the see my security cameras for remote sites. I have income properties in other states.
So, ran a scan with the Comodo antivirus, O (zero) detection. This tells me that the Bitdefender is doing its job, and I am ALL OVER the internet.
Sorry, I can't for the life of me see why anyone would rate this as their number 1 source for protection. It's intrusive, and it nags the heck out of to sign up for the add ons you didn't want in the first place.

Were these messages you saw in the lower-right corner of the screen in a small popup window? If so, then I just added advice on how to disable these advertisements to the article. I apologize, I had meant to mention this previously, but forgot to include it in a previous revision.

Excellent review as usual Chiron. I'd been using the free Avast AV/Comodo firewall combo for about 2 years but problems with Avast updating and your favourable Comodo AV review led me to ditch Avast and replace it with the full Comodo Internet Security free suite. Much less hassle having everything in one place and not having to worry about conflicts and creating exclusions etc. Things are now noticeably quicker.

I'm happy to hear that. It's very nice that users have the choice of whether to use Comodo Firewall with Avast Free. They are a very nice combination. However, I personally also use Comodo Internet Security, and prefer it to any other combination. That said, each computer, and computer user, is different. Thus, the more top-quality options which can be presented the better. Thank you very much for letting us know that Comodo Internet Security worked very well for you. If you run into any problems, or have any questions/suggestions, please do let us know. Thanks again.

One thing I didn't mention was what a nightmare it was to uninstall Comodo firewall to do a clean install of CIS Premium, even using your guide on the Comodo forums (Revo, both removal tools etc). Lost internet connection, CIS wouldn't install and restore wouldn't work due probably to either remnants of Avast or Comodo firewall. I finally got everything to work a considerable time later.

Did you make sure that the firewall driver was correctly removed before rebooting into Safe Mode? Sadly sometimes that is not removed by the uninstaller, and I don't believe the removal tools correctly remove that either. Either way, it is true that Comodo Firewall doesn't always uninstall easily. However, the methods I suggested, which you followed, will allow it to nearly always uninstall correctly. It seems that you ran into some bad luck. By the way, how did you eventually get it to work? Thanks.

You're right about the firewall driver. Neither removal tool nor the uninstaller removed it. Your advice to remove it manually is several steps after rebooting into safe mode, so it hadn't been removed before doing this.

Regarding how I managed to get things to work, things are a little hazy due to a fair bit of red mist, but I went through the uninstall procedure again with Avast (2 removal tools like Comodo) and Comodo Firewall, still wasn't able to install CIS but at least restore then worked so as a last resort I restored to before trying to uninstall Comodo Firewall, and just went through the whole laborious process again and eventually it worked.

I think perhaps I should move the advice about manually removing the firewall driver into the main advice section of my topic. Then again, it's not something which most users would like to do. I'll have to think about it some more, but your experience has given me a lot to think about. Thank you.

Good Day A ! Hi George.J ! I am a current user of 360 IS and am considering switching to 360 TS for support reasons as you know. I'm curious if you could tell me more about your experience with 360 TS compared to 360 IS regarding detection rate, resource usage, boot up time, scan time, and how well 360 TS plays with other software, such as MBM and SAS. Never mind George, I have already found answers to my questions.

Well am back to using 360IS again. The reason is 360TS requires more resources on my system. The TS version uses around 150MB RAM while the IS version is very lightweight, using only around 30MB. Additionally 360TS adds other features like SpeedUp, Junk CleanUp etc, which aren't actually required for me, although it might be useful for others. While 360IS is clean as a whistle, guess it's the best antivirus I've ever used. Sadly the product isn't updated frequently like 360TS version. :( For a comparison betweeen 360 IS and TS in detection check this video review. If you want to watch various community video reviews, you've got 360TS MazaiTest 360IS Review 360TS viktik 360TS without BD and Avira engines> 360TS yigido Overall excellent results from all sides :)