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

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...

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  • Excellent malicious URL blocking, network protection, outdated software checking, integrated password manager, and comes with a rescue disk.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

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

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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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Please rate this article: 

Your rating: None
Average: 4.3 (2159 votes)


For Windows 10 users the latest Bitdefender Free AV coupled with their stand alone BD Anti-Ransomware which is also free offers excellent protection.
Same highest rating results as their commercial product but very lightweight, unobtrusive and free. Not configurable which won't please the geeks but a great option for the average user in my opinion.
The latest version of Bitdefender AV Free will only work with Windows 7 Service Pack 1 through to Windows 10.

For 360 you wrote "light on resources" and yet the essential version i have installed uses nearly 500mb of ram and 900mb of VM on my windows 7 x64.

Strange. It used to use only 60MB when I had a resident antivirus running on my system. And around 80-90MB with Bitdefender and Avira engines enabled out of the total 8GB RAM available. I don't recommend running the Essentials version [TSE] because it's slow to update [still at v8 compared to v9 for TS] and doesn't get all the fixes that Total Security [TS] gets. I haven't tested on Windows 7 though as all these results are from Windows 10.

I am trying to install BitDefender Free
Their 2016 version won't install in XP (or Vista)
I have nearly gone insane attempting to get their FREE XP version (it is the 2015 version)
I managed to get a link (to the 2015 version) from the 2016 failed install.
But I cannot work out whether if that is their free version.
Can anyone point me to the free XP version ?

From the product website: - "Operating system: Windows 7 Service Pack 1, Windows 8, Windows 8.1, Windows 10". Some free solutions such as Avast do still work on XP although protection will be limited at best considering XP is now obsolete and system vulnerabilities are no longer patched. MC - Site Manager.

I find it my self very similar as you described in your reviews. 360 is the best, Comodo has improved a lot in the last years, Avira always been good. But I find it confusing why Quihoo's 360 is not represented in the big AV-Comparatives? Neither Comodo... I recommend you one more antivirus to review: Sophos Home. Is the third biggest security company on the world (behind Norton and Kaspersky), light on resources (cloud), very simple to use and in quite a few tests (Scanning speed, resource management, total hits, etc...) is in the top of the AV softwares.

Qihoo 360 was removed from av-comparative, AV-TEST and Virus Bulletin because they were cheating. You can googled for the news. I'm going to share the link, but when trying to post my comment, it was blocked.

I've tried Sophos Home recently and I am not yet convinced of using it beyond my tests. Detection can be very good but on AV Comparatives it's overall real world detection is similar to Windows Defender, sometimes worse! For resources, on my PC it has 6-8 various components which when idle total around 300mB of RAM, that's a lot and although I have 8GB RAM the PC feels a bit sluggish especially when browsing. It's also a pain having to go into the online control panel to add exceptions and other tasks rather than doing it immediately and smoothly in the client software.

Also re-tried Avira recently. I found it's heuristics to be really excellent, unlike the review above, especially on identifying macro viruses and trojan downloaders which then download Locky and other ransomewhere. In my tests Avira detected all zero day stuff that had just arrived in my mailbox and this was confirmed as brand new on Virustotal and with Avra being in the first bunch of 7-10 detectors out of 55 that quickly, even immediately detected these things. On the downside, once detected, cleanup is very slow which would not be a problem but it leaves lots of remnant files and folders which is confusing and makes the user think that the malware is still there. Also the interface is not only very old but also quite confusing. The seperate program / process of Luke Filewalker is just plain ridiculous in my view, it should be integrated fully and seamless.

Tried most others but currently still on Windows Defender because it has the least impact and the best cleanup but detection although much improved this year needs to be a lot higher.

The latest beta of free Bitdefender looks promising but whilst it remains a beta I won't be trying it.

Avira has not been compatible with XP for more than two years - .

For those still running XP (and which should be utilizing the Registry hack to enable receiving the WEPOS updates -, Bitdefender Free is a lightweight solution that has demonstrated adequate protection on the several machines that I have had it installed on.

I read that Avira has the best privacy policy.

Not for nothing, could you elaborate on how Windows Defender improved in Windows 10 despite the bashing it still, and always gets?

If it is better, why are others still not using it? Or is it the negative, or maybe proven hype?


When I upgraded to W10 Pro, I was prepared to give Windows Defender a try.
My PC is not powerful, and when I noticed it getting sluggish sometimes, I checked and Win Defender was busily scanning my drive (even inside zip files) when no scan had been scheduled or requested.
I like to control what is happening, and when, so Windows Defender is gone.

Qihoo 360 Total Security light? Not here. RAM usage for all processes averages around 70MB (balanced mode, without Avira and Bitdefender engines) compared with around 15MB for my previous AV, Panda Free. 360 TS is far too bloated. Also, less experienced users need to be very wary of what's being deleted/changed if they use any of the optimization tools. Certainly not recommended by me.

360TS uses 70MB on my system with Avira and Bitdefender engines enabled.

How do you turn them on ?

Click on the Protection tab in the Left side bar of the UI and then click on Custom settings. Scroll down and enable any of the engines you like and press OK. Now go to Virus scan tab in the left side bar, and then on the bottom move the slider bar to green over the Avira/Bitdefender engines.

If it was me I would enable them only during on-demand scans, and disable it in real-time.

It's important to note that idle RAM usage is not the only parameter to check if a software is light or not. How an antivirus affects application launches, installing/uninstalling softwares, boot time, archiving and extracting, file copying, downloading from web browsers, processor and ram usage when idle and during scans/updates along with various other factors determine the performance impact of an antivirus.

On a lighter note, Qihoo 360 usually took only around 30MB for me on idle without additional engines. What we can infer from this is that system configuration also plays an important role on the same. Additionally using any optimization software involves some knowledge about the same, but Qihoo's own tools are pretty safe to use and doesn't involve registry cleaning or advanced optimization techniques. But I wouldn't still recommend 360 TSE (Essentials) over 360 TS because it has slower updates and sometimes more false positives for some reason.

Thanks for the quick reply. Reading other glowing reviews and user experiences of 360 TS it does seem I'm in the minority regarding RAM usage. I was wondering if there was a conflict with Zemana AntiLogger Free as 360 TS also has an anti keylogger component but disabling ZAL made very little difference. I'll persevere with 360 TS though because fundamentally it seems pretty good.

I'm not sure how much I trust Qihoo and their products after reading how easily they got duped into whitelisting malware ( Not only that, but the article goes on to point out that "Testing bodies AV Comparatives, AV-TEST and Virus Bulletin decided to revoke all certifications and rankings awarded to Qihoo 360 products last year after they found that the products submitted for testing behaved differently from ones offered to customers."

Thanks for posting the article as well as bringing that to my attention. Qihoo should have double checked the products before whitelisting them. About the revoking of certifications, that's definitely between them and the testing bodies. But when Qihoo 360 TS already does splendidly well with the default configuration that I tested (rather than the modified version submitted to testing bodies) there's little for me to complain about here. But like MC has mentioned before, using software's in their default configuration is unacceptable unless you want to go through the "easy" route. Many users customize the product according to their tastes and hence the level of protection/usability/performance varies according to each configuration. Hence testing products in their default configuration is not exactly the right way to do. It just seems simpler.

How can one trust a company that has found to be cheating by three of the widely respected anti-virus testing companies - AV Test, AV-Comparatives and Virus Bulletin to the extent that all three testers have stripped Qihoo 360 Total Security of their test results.

You can make what you will of the reasons given for the test submissions (Chinese v external market) but ultimately the true detection performance is a matter of configuration.

"Investigations by the three labs found that all products submitted for testing by Qihoo had one of the product's four available engines, provided by Bitdefender, enabled by default, while a second, Qihoo's own QVM engine, was never enabled. This included versions posted to ostensibly public sections of the company’s websites.

By contrast, as far as can be determined, all versions made generally available to users in Qihoo's main market regions had the Bitdefender engine disabled and the QVM engine active. According to all test data this would provide a considerably lower level of protection and a higher likelihood of false positives. Options are provided in the product to adjust these settings, but as the majority of users leave settings unchanged, most tests insist on using the default product settings to best represent real‐world usage."

Maybe most users do leave their settings at default in which case the test results were certainly erroneous. On the other hand, using security apps at default settings quite often yields unsatisfactory results and this is not how Windows security should be configured. MC - Site Manager.

I ran 360 for about a year but got tired of the same annoying issues all the time. It'd get warning pop up about stuff that I'd already white-listed and despite continually saying "yes" over and over again I'd still get the pop-ups. Not to mention that the false positives are just excessive. They are all from the 360 engine, which is always on. It can't be disabled even if you have the other two engines enabled. If you could run it with just the Avast and Bitdefender engines it would be great.

I switched to something that only gets a nod in the honorable mentions here - Sophos. You essentially get their corporate product, complete with cloud-based management, for free for up to 10 computers.

I didn't have a problem with the same application after white-listing it. Since Qihoo has high proactive (behavioral/heuristic/hips) detection capabilities it might show false positives for certain files. Most of which I have seen is from various C++ and Java programs that I have written, and since there is code injection involved it detects as heuristic (possible) malware. But it still doesn't delete those files, but is left upon to user's choice to analyse and determine which files to keep/remove.

The notifications that you might have received and answered "Yes" to might be when an application was trying to access protected areas of the registry. Qihoo has registry protection feature where important areas of registry are being monitored. So those pop-up's you receive might be for individual registry entries related to a specific application. But when you click "Allow all" instead of "Allow" will give access for that software to all related registry areas instead of having to click Yes separately for individual entries. But this does not mean it "white-lists" the software during real-time/on-demand scan. You might have to manually do that by going to Virus scan->Trust List->add related .exe files.

Regarding Sophos, it's good but quite simple for my tastes. For a cloud antivirus it's not light, the install takes more than 900MB disk space (Program Data+Program Files folders) and also has high RAM usage (>200MB). Also the dashboard (controls) are present in a web-like interface accessed through a browser! As for the good parts if you have multiple systems to manage it's sweet. Also it's web protection is great, parental controls are charming with good PUP detection as well as no adware present in it.

360 Total Security should be changed to "Free for private use only". Its website at, under Category>Others, states "The software is not licensed for any commercial business activities, profit-based business activities, or revenue-generating business activities." (Their wording is a bit unclear though.)

I thought Panda was the top rated... I can't keep up.... I had 360 and than found out Panda was better and now Panda is last and 360 is first....DANG!

Dont take all the tests too serious.Panda IS a great antimalware,and its okay light too.It would be my number one choice if I wanted a free antivirus.
Your ass is covered with Panda.

"Better" is mostly a subjective word. Like I already said in the Introduction part there is no Best Free Antivirus so I went through the Pro n Con structured layout in this article to make it easier for you to find an antivirus that best suits your needs.

The best thing you can do is to stick with your current antivirus, most preferably one among these mentioned in the article, while also reading through other alternatives if any particular feature in an antivirus attracts you. Otherwise you can try all of them, and stick with one. This is the best part of any software that's been offered for free.

I endorse 360 Total Security. I was introduced to it when a local print company using it picked up a threat on my USB that MSE had not detected.
now use both it and MSE and find they work seamlessly together.
I also like the Optimise Option on 360