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.

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.

Honorable Mention:


Discussion And Comparison

1. Qihoo 360 Total Security

The Good:

  • 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
The Bad:
  • 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
The Ugly: 
  • Nothing for the moment
The Truth: Rating 10 of 10 5/5 stars
 Home |  Download |  v8.2 |  bit version |  Fully freeware |  41.6MB |  Win XP-10, Mac OSX

2. Avast Free Antivirus

The Good:

  • 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
The Bad:
  • 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
The Ugly:
  • Offers Google Chrome and various bloated secondary components during install [Choose custom install]
The Truth: Rating 9 of 10 4.5/5 stars
 Home |  Download |  v11.1 |  bit version |  Feature limited freeware |  193 MB |  Win XP-10, Mac OSX

3. Comodo Internet Security Premium

The Good: 

  • 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
The Bad: 
  • 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.
The Ugly: 
  • Chromodo browser, Yahoo search engine, custom DNS and Geek Buddy offered during default install. [Click customize installation during install]
The Truth: Rating 9 of 10 4.5/5 stars
 Home |  Download |  v8.2 |  bit version |  Unrestricted freeware |  208 MB |  Win XP-10, Linux, Mac OSX

4. AVIRA Free Antivirus

The Good:

  • 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
The Bad: 
  • 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
The Ugly: 
  • Nothing for the moment
The Truth: Rating 8 of 10 4/5 stars
 Home |  Download |  v15.0 |  bit version |  Free for private use |  200 MB |  Win XP-10, Mac OSX

5. Panda Free Antivirus

The Good:

  • 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

The Bad: 

  • 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

The Ugly: 

  • Watch out for Panda security toolbar during install
The Truth: Rating 8 of 10 4/5 stars
 Home |  Download |  v16.1.1 |  bit version |  Free for private use |  61.4 MB |  Win XP

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Average: 4.3 (2152 votes)


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.

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?