The 10 Best Free Antivirus Software of 2021

Avira Free Security

The main component in Avira's free software suite that makes it stand out is the optional "in-the-cloud detection" feature called Protection Cloud. This scanning method lets Avira's antivirus tool identify and stop threats before they get out of hand.

This is how it works: When a suspicious file is detected on any computer running Avira, a fingerprint of that specific file is generated and uploaded anonymously to Avira so that they can scan it and report its status (whether it's safe or dangerous) back to every Avira user so that the program can take appropriate action. 

Avira can scan and remove existing threats as well as automatically detect and stop new ones. It protects you against ransomware, Trojans, spyware, and other kinds of malware. You can even choose which ones to actively watch out for, and disable others (though it's not recommended) like dialers, jokes, adware, etc.

Avira Free Security can also scan on a schedule, check files with any file extension or just the ones you manually choose from, disable the ability to stop active scans (so that viruses can not stop the program from finding them), adjust the scanner's priority level, scan primary boot sectors, follow symbolic links to scan the actual files, search for rootkits before starting a scan, scan the Windows Registry, ignore files on network drives, automatically repair, rename, quarantine, delete, or ignore threats when they're found, use heuristic scanning, add files, folders, and processes to the ignore list, manage Windows Firewall settings, password protect the program's settings, block autorun on removable devices, and make the hosts file read-only.

This program offers more than just a very extensive antivirus application. It includes several other "layers" of security that will install automatically, and they might take a while to download since there are several. However, you don't have to use them, and they won't bother you unless you open them.

These separate modules include a VPN that encrypts all your traffic (up through the first 500 MB each month); password manager to securely store complex passwords; and software updater that identifies outdated programs and gives you the download links to update them. 

In addition, Avira can speed up your computer and reduce boot time with its tune-up tool, help you find the best deals as you shop online, and warn you of malicious websites or software bundles before you download them (with its SafeSearch add-on).

These extra features can be annoying if you're strictly after an antivirus solution, but again, you don't have to use them; just keep them tucked away where they are, and you won't have to worry about them.

Avira Free Security is intended to run on computers with Windows 7 and newer; this includes Windows 11, 10, and 8. There's also Avira for macOS.

Bitdefender Antivirus Free Edition

If you want an antivirus program that's not only free but easy to use and not cluttered with lots of buttons and menus, you should definitely try the free version of Bitdefender Antivirus. 

You not only get instant protection against viruses, worms, rootkits, spyware, and other threats, but also anti-phishing and anti-fraud protection to carry security with you when you're browsing the internet and entering passwords.

It's remarkable how well Bitdefender runs despite its minimal design. Drag and drop folders and files directly into the program to run a scan against them, as well as start a full system scan or scan select objects from the right-click context menu—all of which can run at the same time.

Regardless of how they're started or how many scans are running simultaneously, a history of those scans are recorded for you on the primary window of the program as well as within the Events area of the settings. 

The obvious downside to a program that lacks many customization options is that there isn't much you can change about it. That might be something you want, but it might not be available—all you can do with this edition of Bitdefender is start and stop scans.

Another downside to this software is how long it takes to become ready for you to use. The initial installer for Bitdefender is quite small, but that's just what's used to then download the full program, which is hundreds of megabytes and could take a while if you have a slow internet connection. 

It's also unfortunate that you can't pause scans (it just lets you stop them) or set up file and folder exclusions before starting scans like some AV programs allow. With Bitdefender, you can only mark files or websites as safe after they've been identified as potentially malicious.

Ads asking you to purchase Bitdefender's professional programs and scheduled scans not being supported (but they're not necessarily needed since Bitdefender is always checking for new threats) are a few other not-so-greats.

Bitdefender Antivirus Free Edition is said to run on Windows 10, Windows 8, and Windows 7.

Adaware Antivirus Free

Adaware Antivirus installs in minutes, is light on system resources, and can be used in one of two ways. The first is in regular mode where it checks for threats as they happen, but the other lets you use it in addition to your primary antivirus program.

What this so-called "second line of defense" does is disables real-time protection but still lets you use Adaware Antivirus to manually scan for existing threats. This feature is helpful if your primary AV software doesn't seem to find malware that you know is infecting your computer.

Whichever way you use it, Adaware Antivirus provides a defense against ransomware, spyware, viruses, and other forms of malicious software. You can find those threats through a quick, full, or custom scan.

Daily, weekly, and monthly scheduled scans are supported, and you can even run a scan to just check certain things, like only rootkits or just tracking cookies and boot sector viruses, for example.

Adaware Antivirus also lets you choose a custom performance setting to use more system resources to run the scan (to make it faster), exclude files/folders/file extensions from scans, and decide how often to check for new definition updates (every 1/3/6/12/24 hours).

For real-time protection, you can toggle on or off the following options: scan archive files, scan email databases, deep scan that checks CHM files and executable files, smart scan that skips previously checked files, scan boot sectors, scan files as they move throughout the network, and skip scanning files that exceed a custom file size (e.g., 10 MB to skip video files).

You can also protect the program's settings with a PIN as well as enable gaming/silent mode to suppress notifications.

Adware Antivirus definitely has its advantages but because there's also a non-free version you can upgrade to, many additional options are not supported.

For example, parental controls and advanced network, web, and email protection are only available in Adaware Antivirus Pro. These options are visible within the free edition, but they're not actually clickable/usable until you enter a Pro license key.

Adaware Antivirus Free works with Windows 10, Windows 8, and Windows 7.

Avast Free Antivirus

Avast is used by hundreds of millions of people and ranks high in nearly every "best list" of antivirus programs, and for good reason. If you want a solid program that is sure to block new threats but is still easy enough to customize, you should consider using it.

Avast Free Antivirus is similar to Avira; supplemental modules enhance the virus shield and provide additional services related to security and privacy.

The antivirus portion has lots of options you can change but it's still easy enough for anyone to use since there are information blurbs next to most items so you're not left wondering what will happen if you enable them.

Plus, both definition and program updates are performed automatically (a manual option is available, too), meaning you can install Avast and let it do its thing without worrying whether you're running the latest and greatest version.

Avast is customizable and lets you make changes to everything from whether to make a sound when threats are detected and how long notifications should remain on the screen, to the kinds of file extensions that should be scanned.

Here are some more features supported in this program: scheduled scans, custom scans that can check only the memory, rootkits, auto-start programs, etc., checking all files or just certain file extensions, protecting against ransomware, identifying files by their content instead of their suffix, fine-tuned heuristics sensitivity, scanning for potentially unwanted programs, follows shortcuts to scan the real file, scan archives like self-extracting DOS and Win32 executables and 7Z and RAR, Windows Explorer context menu integration, exclusions for folders, HDDs, and URLs (but not specific files), custom scans that are easy to save for use in the future, a Rescue Disk utility lets you use the Avast scanner even if you can't start your computer, particular areas of the program can be protected with a password, and Do Not Disturb Mode.

Before Avast is installed, you have the option to include over a dozen different tools: file, behavior, web, and mail shields; software updater, browser cleaner, rescue disk, Wi-Fi inspector, security and SafePrice browser extensions; password manager; junk file cleaner; and Game Mode.

Technically, if you only want the antimalware protection, you can install just the shields from the start of that list; the others are add-ons that aren't necessary but could be helpful at some point.

For example, the software updater is a nice tool that will not only check for and report outdated software but also install the newer versions for you (even in bulk).

Wi-Fi Inspector scans the network for devices that could be vulnerable to attacks. For instance, it might identify that a computer is running a file sharing service that has been known to facilitate the spread of a certain kind of worm.

You can install these tools (it takes less than five minutes) and then disable or completely remove them later. Or, you can ignore them during setup and just install them later, or not at all.

However, the password manager and Cleanup tools are only trial versions that will expire after a time-limited trial. There's also a firewall, file shredder, and sandbox feature that's unusable in this free version.

Avast Free Antivirus is compatible with Windows 10, 8, and 7. There's also a version for macOS, Android, and iOS.

Panda Free Antivirus

Panda Security's free antivirus program installs in minutes and has a minimal design like Bitdefender. However, even though it's not a CPU or memory hog, and doesn't appear to be customizable, all of its many options are tucked away in the program's settings.

From there, you can do things like set up both on-demand and automatic scans to check compressed files and scan for potentially unwanted programs.

The automatic, permanent scanner includes some additional options, too, like behavioral and analysis scanning options, the ability to ask you before neutralizing a virus, and blocking files from running for so-many seconds until results on whether it's safe or harmful are obtained from the cloud.

Something entirely unique to Panda Free Antivirus is its security news and alerts sections that can show you critical, warning, and informational messages like when a popular vendor experiences a data breach that could affect your personal information. You can, however, turn those off if you want to.

Complete a scan in just a few minutes if you only want to check for actively running threats, like browser cookies, processes, and things currently loaded in memory. However, there's also, of course, an option for a full system scan or a custom scan.

Here are some other things you can do: password protect the entire application, have the quarantine emptied every so often, disable notifications when in full screen, exclude files/folders/extensions from scans, enable USB protection to scan removable devices as they're attached, monitor running processes as well as any URLs accessed by them, record everything in event reports that you can browse through and print or export to a TXT or CSV file, use Panda Safe Web to protect from malicious websites, and use their free VPN for limited daily traffic.

This software does a fantastic job at keeping the important buttons up front and hiding the additional options within menus so that you're not constantly bombarded with options or alerts.

However, the program will change your home page and the search provider in your web browser, unless you uncheck those options during the initial setup.

The minimum operating system requirements for installing this program are Windows 10, 8, 7, Vista, or XP. It should work equally well on Windows 11, too.

AVG AntiVirus Free

AVG's free antivirus program is easy on the eyes and even easier to use. The scan button is right in the middle of the screen, turning features off is dead-simple, and all the advanced options are tucked away from view in the settings.

Like most antivirus tools, this one lets you schedule scans, check for threats in archives, remove viruses right when they're found, scan USB drives, exclude files/folders/websites from scans, and run boot-time scans.

AVG AntiVirus Free is highly customizable. You can either install it and leave the settings alone to have regular protection, or go into the settings and make adjustments to nearly anything.

Choose how to scan files— include only content that might include malware (like executable data), only files that use a file extension considered potentially dangerous (like EXE), or all files regardless of content type or file extension.

Enable rootkit detection, hardcore mode, and CyberCapture technology, which helps detect threats in unrecognized files.

During setup, you have full control over which components should be enabled or disabled after AVG is installed. Options include File Shield, Behavior Shield, Web Shield, Email Shield, SafePrice browser extension, File Shredder, Cleanup, and Do Not Disturb Mode.

AVG AntiVirus Free includes a file shredder tool as well, which you can use from the right-click context menu to overwrite files using the Random Data, Gutmann, or DoD 5220.22-M data sanitization method.

Windows 10, 8, 7, and XP are the official minimum OS system requirements. It also runs on Mac (10.10 Yosemite and newer), Android, and iOS.

COMODO Antivirus

COMODO Antivirus excels in a few ways: it can be as simple or as complex as you want it to be depending on your experience level with antivirus tools, it supports cloud-based scans to detect new threats, and the built-in sandbox technology can isolate programs so that they can’t affect your files even if they do turn out to be malicious.

Right after installing this free antivirus program from COMODO, a scan starts to make sure your computer is safe. You can also run scans at any time, either quick scans, full scans, scans of commonly infected areas, and custom scans.

A custom scan in COMODO Antivirus lets you choose which files or folders to scan and enables a host of other customizations like whether to decompress and scan archives, use cloud scanning, automatically delete threats, enable heuristics scanning, check for threats running in memory, skip files over a maximum size, run the scan with full system resources, delete PuPs, and more.

The basic view for the program's settings runs scans, unblock applications, updates the program, and runs software in a virtual mode, while the advanced view reports more details about those areas of the program and displays logs as well as toggles various things like HIPS and VirusScope.

Check out the virtualization feature in COMODO Antivirus. You can run any program you want in a virtual space completely separate from the rest of your files. It’s an opportunity to test out an application to ensure that it’s real and not just a trick to get you to install a virus. Launch programs in this protected container from inside the COMODO program, or by right-clicking an executable file and choosing the option in the menu.

Here are some other features worth mentioning: password protect the program, show a floating desktop widget, hide the upgrade advertisement, choose which archive file types to unpack and scan, enable real-time scanning of files on the network, define heuristics scanning level (low, medium, high), schedule scans as frequently as every hour to as infrequently as once a month, customize the HIPS rules, turn on Silent Mode, force the auto-containment of suspicious or malicious files, and use a unique password for the Virtual Desktop feature.

COMODO Antivirus is officially compatible with Windows 10, Windows 8, Windows 7, Windows Vista, and Windows XP. It's also available for macOS and for Linux.

Immunet AntiVirus

Immunet offers real-time protection for Windows. It has a bit of an outdated interface but the software is still current and even connects directly to the cloud for updates.

There are lots of options you can toggle on or off to customize how the software works, but you can also leave all the defaults and it will still check your computer for threats in real time.

Here are some other features you get with Immunet: detects and removes bots, viruses, worms, Trojans, keyloggers, and spyware; three scan modes let you check just running processes (Flash Scan), any location of your choosing (Custom Scan), or the entire computer (Full Scan); schedule any scan type daily, weekly, or monthly; start scans directly from Explorer on any folder or file; run a FlashScan right after installation to check the registry and running processes for threats; use a special blocking mode that prevents all programs from being installed unless they first pass a security scan; prevent notifications from the program while you watch movies or play games; automatically exclude certain folders and file types from scans, including temp folders and certain system32 folders; manually exclude any file, folder, or threat (by its name); toggle scanning for archives and packed files.

There's also a handy timeline that shows the history of threats on the computer, to 30 days in the past. The extremely detailed history of events that have happened in the program can be filtered by date, keyword, and type (such as quarantines, cleanings, blocked processes, etc.).

This program runs alongside many other antivirus programs, such as security software from Comodo, Avira, AVG, and Norton.

Immunet AntiVirus has been tested on Windows 10, Windows 8, and Windows 7, as well as Windows Server 2016/2012/2008 R2.

Kaspersky Security Cloud Free

Kaspersky Security Cloud Free is a good choice for a free antivirus program if you want a simple program that boasts lots of features. It’s easy to use and offers many advanced options if you care to look into them.

This free AV program is also useful if your computer is low on system resources. Kaspersky Security Cloud Free can automatically postpone scans and reduce display animations if the CPU runs too high. It supports idle scans for when you’re away and lets you favor performance over protection by altering the overall security level.

It includes Self-Defense, which is a function that blocks all attempts to change or delete Kaspersky’s processes, registry items, and installation files.

Other details worth mentioning include the ability to search for rootkits and can delete malicious tools, adware, auto-dialers, and suspicious packages; password protect the program to protect its settings from being changed or to stop it from being uninstalled or shut down; use a file and web scanner as well as Network Attack Blocker, System Watcher, and Mail Anti-Virus; enable gaming mode to suppress notifications while using any program in full-screen mode; auto-pause the scanner when specific applications start up or during certain times of the day; choose what happens when a threat is detected: notify, disinfect, delete if disinfect doesn’t work, or delete; auto-scan external drives or prompt you to scan them when they’re inserted; and schedule quick or full scans for every day, every weekend, every weekday, weekly, or monthly; choose what gets scanned in a full, quick, and selective scan; skip items if the scan takes too long; speed up antivirus scans by checking only new and changed files; exclude files and folders from scans, and even prevent the scanning of specific threats; and define trusted applications so that they're not scanned.

Kaspersky's free antivirus program runs on Windows operating systems; it's said to be compatible with Windows 10, 8, and 7. There's also an app for Android and iOS that goes by the same name.