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  • Excellent malicious URL blocking, network protection, outdated software checking, integrated password manager, and comes with a rescue disk.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

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Average: 4.3 (2219 votes)


I think here is three of the best free antivirus software for multi-platform, including Windows, Mac OS X, Android and iOS.

- Avast
- Avira

The RogueKiller website has a well structured and comprehensive article that goes into a lot more detail but is relatively easy to read if you bypass the programming examples: Making an antivirus engine : the guidelines.

I recently dumped Avast after many years simply because of the annoying advertising pop-ups. After reading the recommendations by Chiron for Comodo, I installed it and have had it running for a few days now. No problems with it except for the deceiving tactics by Comodo during the install process.
Despite selecting "custom install" and unchecking the boxes that I didn't want, Comodo ignored that and installed everything.... I had to manually get rid of geek buddy and the Comodo browser.
How can this forum recommend software that continually breaks the rules ?

Were you that annoyed with the pop-ups? I have Avast on my system, and I think the pop-ups occur only when the definitions are updated. Although their size has increased, still, I do not find them annoying. It's something I can do with, considering the fact that the antivirus is great, and free.

G'day Anupam,

When I first installed Avast about 3 years ago, everything was good.... it was quite unobtrusive and yet quick to strike on any bad guys.

In the past year or so, with the regular updates from Avast, it seems to have become bloated and whilst I was still very happy with the protection it provided, it did become intrusive , the constant pop ups telling me that there were X amount of problems/issues with my PC seemed like a ploy offered by many shonky software programs that diagnose your PC, find many problems and then offer to fix them for a fee of course !
The Avast pop up invited me to click on a button to fix the issues with my PC and instantly I was greeted with a new message advising me that it would cost for the premium features to carry out this task.
Doesn't matter how many times I declined, the pop ups kept coming.
Bottom line ?..... yes, the pop ups did start to annoy me.
I know that Gizmos site does not endorse any paid-for commercial product and I believe that the free version of Avast is pushing the boundaries here with its constant nagging to upgrade to the premium version.
Meanwhile, I have Bitdefender free version running..... it's so unobtrusive and sometimes I wonder if it's doing anything but it has detected and quarantined 6 items since I installed it about a week ago. The only thing missing from it is email scanning but that doesn't bother me.

Good day terrawarra :). The issues you post about, I haven't encountered on my system. I do get the popups though, and I simply close them.

Avast Free nowadays comes with several components/tools, like updater, etc, which perform extra work. I do not install any of these. I suspect that you have some or all of these installed, and the popups you mention, are occurring because these components are installed. In future, if you install Avast, deselect the unncessary (or all) components, and just select the shields that you want, and it should be fine.

Thanks Anupam,
I may try Avast again sometime in the future and give it another chance.
In the meantime, I'll give BitDefender a fair trial, assess the results and decide which one I want to go with.

We are indeed quite spoilt with so many quality freeware anti virus products out there.


Yes, there are good free antivirus nowadays. But, I guess it depends on individual taste, which antivirus you install on your system. I occasionally try different antivirus, but I keep returning back to Avast, since it is what best suits me. It is lightweight, provides good protection, and has boot time scan. All other antivirus that I tried, I had some issues with them, big or small. Avast suits me best.

With so many choices, you can always try different ones and settle on one which suits you most.

I dont' use Avast anymore but while I used it in the past, I don't think I had the pop-up troubles that you experience. The way you say it, it's what I feel about Avira in the past, but Avira has stopped with it's ads and stuff, and is a clean product today.

I have switched to Qihoo 360 since an year or two, and one thing I feel great about a totally freeware product like this is that, not only you get all the features for free, you don't get reminders to switch to the commercial version. 

I downloaded the installer today from the link on our page. The file was: cav_installer_3272_7b.exe (204.1 MB). I selected the language and unticked the options for cloud based behavioural analysis and anonymous usage statistics. I then chose "customize installation" and unticked the options for GeekBuddy and the Comodo browser (Comodo Dragon was already installed on my system which is why it appears in the program list) Proceeding with the installation I also unchecked the options for using Comodo DNS and the search engine change. The result was a clean install with nothing else added or changed. If you research this properly you will find that GeekBuddy can also be included with a third party wrapped installer, so if you obtain the program from a different source, it is still possible for this to be installed even though this option in the Comodo install process was denied. MC - Site Manager.
This happened to me once in the past, even after choosing custom options, GeekBuddy still got installed.

Thanks George and MC.... it's obvious that we don't live in a perfect world so I can cop the odd glitch from software that's free.

About two months ago, I had to wipe my computer and reset to factory specs, after a virus-related issue I just couldn't get rid of. (Happens about once a year for me. Means I'd like to see the death penalty for all virus writers.)

For the last two months I have been letting the built in trial version of one of the companies that doesn't have a free virus option cover my system, while backing it up with Spybot (for the immunization protection), Ad-Aware (just because it has been one of my back-up options for ages) and MalwareBytes because it cleans up almost anything.

Today, the trial software (which still had four days left) turned itself off, and turned off my firewall, too. I did scans with all four products, none finding anything, removed the trial virus program, and installed BitDefender as my 'active' program, with the other three still being regularly used manually to scan for problems.

Considering adding Avira as just another 'try it once a week or so, looking for any problems.'

Since MalwareBytes is almost always my first thing to throw at anything that acts weird, most of the others never get a chance to find anything, but I still lake the extra options to try and make sure everything is good.

Any thoughts or comments?

It is never advisable to install more than one antivirus program. There are umpteen posts from reputed sources on the web about this, these being just a few. Secondary scanners that are designed for this purpose are fine, but there are also risks associated with installing a second real-time product and then disabling the active protection. In any case, it is always better to prevent infection rather than trying to clean up after one. The best strategy therefore is to understand how and where from you became infected previously and then tailor your PC usage to avoid further repetition. Having 10 scanners on board still won't help if there is an underlying usage trend to become infected. You might find these articles of interest. MC - Site Manager.

I have been using Panda for some months without issues, but yesterday it updated itself to a new version with a different name. After this, my Privatefirewall could not start anymore, even after a new install (PrivateFirewall Ndis Filter Installer - Install Error 0x80870002).
Looks like the new Panda is incompatible with Privatefirewall.
After removing Panda, Privatefirewall is working fine.
I'm posting this information in case it can be useful to someone else with the same problem.

You could have tried shutting Panda down while installing or move the new PF installer to a folder that you can exclude from Panda.

Have you reported this issue to Panda so that they can investigate and fix it?

Which acceptable av uses the fewest resources, especially memory?

The differences between them might alter every time a new program update is issued.

It also depends on whether you use all of the offered components, I don't.

Last time I checked, BitDefender Free had the lowest usage but it was also the least configurable. My choice is a custom install of Avast Free, I just select the parts I need and then configure it to my needs.

Might do well to remove Panda AV altogether from the list.

An AV specialist that actually identifies itself as a virus is a joke -- though not for the many, many thousands yesterday who were comprehensively sat upon by the blasted Panda. Including myself.

I've run Panda Cloud AV ever since it was released. I'm also aware that stuff happens. But an AV specialist making so huge a blunder as this has me worrying just what kind of sloppiness goes on there -- and what kind of disaster might come along next. 'Bye, Panda. Some one-off glitches are waaay too serious to take a chance that they won't happen again .

Panda of course are not the first AV listed here to have suffered a similar fate and no we will not be removing it nor would we recommend users running Panda to change. In any case, a remedial fix was issued almost immediately. MC - Site Manager.

I had remove Comodo after reading the Privdog that come with it.

Although the Privdog version bundle is not the version that is vulnerable but I do not trust Comodo anymore, specially both Comodo and Privdog are same CEO, and I remember clearly that I had dis-select Geek Buddy, Privdog when install Comodo, yet I still find the Geek Buddy Icon on Desktop and Privdog secretly install.

Just google "Adware Privdog worse than Superfish"

Two articles that discuss this are:

"Privdog is Superfish all over again" - and,

"Don’t use Comodo, Their Crapware Completely Breaks the Fundamental Security of the Web!" - .

A new version has just been released. "This new version addresses issues with keys; keys sizes have been increased to 2048 to comply with a higher standard and improve browser compatibility. Existing users will be upgraded automatically or users can download the update. As always we recommend all users update to the latest version. In the next few days we’ll release version 3.1 with additional features allow users to disabled the HTTPS inspection if they choose to do so. We are also implementing an HTTPS Threat Vector list that will automatically bypass HTTPS inspection for the vast majority of safe web sites". MC - Site Manager.

While I really like the Comodo apps, I do think its write up should note its "extra" things installed if you do not catch the tiny text (a not obvious, easily detectable way to do that) leading to a separate screen to exclude them. Such is noted for some of the other products.

A Geekbuddy component is one of the extras installed if you do not notice the small text under a BIG button to proceed, and there is another extra I do not remember.

5 Common Myths about your Antivirus A really interesting video from a website that I visit daily. Myth 1: Detection Rate is Everything - False Myth 2: If an antivirus detects a threat as being malicious, the file is definitely malware - False Myth 3: Paid is always better than Free - False (for home) Myth 4: You cannot use 2 antivirus at the same time - Usually True (but completely misinterpreted) Myth 5: More "Security" the better - False
Qihoo Internet Security 5.0 released. They don't update the IS version webpage though, it still shows at 4.9 The Total Security is at version 5.2 Stable and 6.0 Beta, but it's good to see the lightweight Internet Security version is still getting developed.

I have been using avira for ages but recently they have overdone it with the offer pop-ups. I tried comodo but you have to teach it everything from scratch. So I'm thinking to try panda but I also don't like much automation (I know! I'm hard to satisfy). Actually I find avira fine in configuring and automation. Can anybody please tell me whether panda is more automated than avira? I mean I would like my AV to ask me of what to do when something is detected. Can this be configured in panda?

Your comments, especially regarding Comodo, suggest a confusion between the normal antivirus and HIPS functions (where included) of security programs. IMO if someone is capable of determining the correct actions to take for every event, then a correctly configured standalone HIPS such as Malware Defender could be used instead of an antivirus program. In reality though a broad spectrum antimalware solution containing multiple detection methods will always be the preferred solution although this inevitably involves a degree of automation. Panda scores highly with both AV Test and the AV Comparatives Real-World Protection tests. Yes it is more automated than some but IMO this is how it should be, especially for normal home users many of whom will not have the knowledge, or desire, to operate their security programs manually. MC - Site Manager.