16 Best Completely Free AntiVirus to Use

Microsoft Defender Antivirus is the best free antivirus for most Windows 11 users. It is built into Windows, provides continuous real-time protection, and received the maximum protection, performance, and usability scores in AV-TEST’s March and April 2026 evaluation. Users who prefer a third-party product should consider Bitdefender Antivirus Free for a focused experience or Avast Free Antivirus for more additional features and stronger current evidence for the exact free edition.

“Free antivirus” can mean several different things. Some products provide permanent real-time protection, some only remove malware after you start a scan, and others are merely temporary trials of paid software. This comparison separates those categories so you know what will actually protect the PC after installation.

No antivirus catches every threat. Keep Windows and other applications updated, use unique passwords and multi-factor authentication, maintain offline or versioned backups, and treat unexpected attachments and login pages cautiously.

Our quick recommendations

Best for most people: Microsoft Defender Antivirus
Best focused third-party option: Bitdefender Antivirus Free
Best feature-rich option with direct free-edition test evidence: Avast Free Antivirus
Best second-opinion scanner: Malwarebytes Free

Best free antivirus compared

Important note about the evidence

AV-TEST’s April 2026 results directly named Avast Free Antivirus, AVG AntiVirus Free, and Microsoft Defender Antivirus, with each receiving 6 out of 6 for protection, performance, and usability. The same report tested Bitdefender Total Security, Avira Internet Security, and Malwarebytes Premium rather than their free products.

AV-Comparatives’ February to May 2026 real-world test directly included Avast One Free Antivirus, AVG AntiVirus Free, and Microsoft Defender. Its Bitdefender, Panda, and Malwarebytes entries were paid editions. Lab results therefore provide stronger edition-specific evidence for Defender, Avast, and AVG than for the other free products in this guide.

How we selected these products

To qualify for the main comparison, a program had to provide permanent free real-time protection for Windows, not merely a trial or manually started scanner.

We considered:

• Current official availability
• Windows 11 support
• Real-time protection
• Recent independent test results
• Whether the exact free edition was tested
• False-positive performance
• System impact
• Important free-tier restrictions
• Account and installation requirements
• Privacy and trust history
• Whether the product remains practical for an ordinary home user

This is a research-led comparison of current product information and independent testing. We have not claimed original live-malware testing, and we do not transfer a paid suite’s exact test result to a different free edition.

Lab reports should also be read as snapshots. AV-Comparatives notes that results apply to the specific versions and test systems used, and its performance report explicitly recommends that users evaluate products on their own computers.

Is Microsoft Defender enough for Windows 11?

For most ordinary Windows 11 users, yes.

Microsoft Defender Antivirus continuously scans files and programs as they are accessed or executed. Cloud-delivered protection can provide continuously updated detection improvements, and Windows automatically turns Defender off when a compatible third-party antivirus registers successfully.

Its current results are also competitive. Defender earned the maximum 18 points in AV-TEST’s April 2026 evaluation. In AV-Comparatives’ February to May 2026 real-world test, it protected against 99.0 percent of the 400 cases and produced no false positives in that test.

Defender is particularly suitable when you:

• Keep Windows and applications updated.
• Use a modern browser with reputation and phishing protection.
• Avoid untrusted software and pirated downloads.
• Maintain reliable backups.
• Do not need a bundled VPN, password manager, or extensive family controls.
• Prefer not to install another security application.

A third-party antivirus may still be useful when it provides a feature you specifically need, such as a different web-protection layer, centralized protection across several operating systems, USB rescue tools, or a preferred user interface.

How to check that Microsoft Defender is active

1. Open Start.
2. Search for Windows Security.
3. Select Virus & threat protection.
4. Check that no action is required.
5. Open Manage settings.
6. Confirm that Real-time protection and Cloud-delivered protection are enabled.

Do not install another antivirus solely because a product vendor claims Windows protection is “basic.” Independent results show that Defender is a credible baseline, although no product is perfect.

1. Microsoft Defender Antivirus: Best for most users

Best for: Users who want strong protection without installing another program
Real-time protection: Yes
Current direct free-edition lab evidence: Yes
Main limitation: It does not include the broad bundle of commercial extras offered by some third-party suites

Microsoft Defender is already part of Windows 11, requires no separate antivirus subscription, and integrates with the Windows Security application.

Its strongest advantage is simplicity. There is no additional installer, separate renewal cycle, or second security dashboard to manage. Windows handles security-intelligence updates and keeps real-time protection running unless another compatible antivirus takes over.

Defender also performed well in both major 2026 evaluations used for this article. AV-TEST awarded it full marks, while AV-Comparatives recorded a 99.0 percent protection rate and no false positives in its February to May real-world test.

Where Defender is weaker

Microsoft Defender is not necessarily the lowest-impact product in every benchmark. In AV-Comparatives’ April 2026 performance test on a low-end Core i3 system, Avast and AVG received a lower overall impact score than Microsoft. The organization cautions that results are specific to the tested versions, machine, and activities, so this should not be interpreted as a universal speed ranking.

It also lacks the extensive bundled VPN, cleanup, identity, and cross-platform tools used by commercial security suites to differentiate themselves. That can be an advantage for people who prefer fewer additional applications.

Verdict: Keep Microsoft Defender unless another product provides a specific feature or experience that you value more.

2. Bitdefender Antivirus Free: Best focused third-party option

Best for: Users who want a permanent third-party antivirus without buying a suite
Real-time protection: Yes
Current direct free-edition lab evidence: No, not in the cited 2026 reports
Main limitation: A Bitdefender Central account is required

Bitdefender Antivirus Free is genuinely free rather than a temporary premium trial. Bitdefender says the product has no hidden costs or required trial and confirms that installation requires creating a Bitdefender Central account. Its free product includes scanning, removal, and behavior-based Advanced Threat Defense.

It is the most attractive third-party choice for readers who do not want an antivirus wrapped inside a large collection of utilities.

Important test limitation

Bitdefender performed strongly in the current lab reports, but those reports list Bitdefender Total Security, not Bitdefender Antivirus Free. AV-TEST gave the paid suite full marks, and AV-Comparatives recorded strong protection from the paid product, but those exact scores should not be presented as direct measurements of the free edition.

The products may share important underlying technologies, but paid and free editions can differ in web filtering, ransomware controls, configuration, and other protection layers.

Choose Bitdefender Free when

• You want a third-party antivirus with a narrow purpose.
• You do not need a large utility bundle.
• Creating a vendor account is acceptable.
• You prefer fewer visible extras than the larger free security suites.

Skip it when

• You do not want to create a separate account.
• Direct current testing of the exact free edition is essential to your decision.
• Microsoft Defender already meets your needs.

Verdict: The best focused alternative to Defender, with the caveat that the strongest current public test results name Bitdefender’s paid suite rather than the free edition.

3. Avast Free Antivirus: Best feature-rich free option

Best for: Users who want additional free protection features
Real-time protection: Yes
Current direct free-edition lab evidence: Yes
Main limitation: More commercial surfaces and an important historical privacy issue

Avast’s current free Windows product provides real-time antivirus and advertises features including email protection, hack alerts, and Wi-Fi security scanning. Avast states that the antivirus remains permanently free.

Unlike several competitors, the exact free product has current independent evidence.

AV-TEST gave Avast Free Antivirus full marks for protection, performance, and usability in April 2026. AV-Comparatives directly tested Avast One Free Antivirus from February through May 2026, recording 99.3 percent protection and five false positives. Its April performance test also directly included Avast Free Antivirus.

That makes Avast one of the easiest free third-party products to support with current, edition-specific evidence.

Avast privacy history

The privacy history must be part of an honest recommendation.

The U.S. Federal Trade Commission finalized an order in 2024 banning Avast from selling or licensing browsing data for advertising purposes and requiring a $16.5 million payment. The matter concerned historical data practices involving Avast’s Jumpshot subsidiary.

Avast says it closed Jumpshot and stopped that data operation in January 2020. Its settlement information states that the investigation involved historical provision of Avast and AVG product data and says Avast does not currently sell consumer data.

The episode is historical, not evidence that Jumpshot still operates. It nevertheless remains a legitimate trust factor for readers choosing security software with broad access to their devices and browsing activity.

Choose Avast Free when

• You want more extras than Microsoft Defender provides.
• Direct current testing of the actual free edition matters.
• You are willing to review installation choices and paid-feature prompts.
• The historical privacy issue does not rule it out for you.

Skip it when

• You prefer the smallest possible commercial footprint.
• You do not want free and premium features mixed in the same interface.
• Its privacy history outweighs its current protection results for you.

Verdict: The best-supported feature-rich free antivirus in current public testing, but not the most privacy-neutral recommendation.

4. AVG AntiVirus Free: Best alternative Avast interface

Best for: Users who prefer AVG’s product presentation
Real-time protection: Yes
Current direct free-edition lab evidence: Yes
Main limitation: It uses the Avast engine and is not a genuinely independent alternative

AVG AntiVirus Free provides real-time Windows protection against malware and promotes protection against unsafe email, websites, ransomware, and online scams.

Its current test results closely resemble Avast’s. AVG AntiVirus Free received full marks in AV-TEST’s April 2026 assessment and achieved the same 99.3 percent protection rate and five false positives as Avast in AV-Comparatives’ February to May test.

That similarity is not coincidental. AV-Comparatives states that AVG uses the Avast engine.

Avast versus AVG

Do not install Avast and AVG together. Installing both does not provide two independent detection systems and can create the usual conflicts associated with running multiple real-time antivirus products.

The practical decision is therefore based on:

• Which interface you prefer
• How each free product presents premium features
• Which installation and notification experience you find less intrusive
• Regional differences in product packaging

The historical Jumpshot disclosure also matters here. Avast’s settlement FAQ says the investigation covered historical provision of Avast and AVG product data and identifies affected Avast and AVG components.

Verdict: A strong current free antivirus, but choose it instead of Avast, not in addition to Avast.

5. Avira Free Security: Best for additional utilities

Best for: Users who want antivirus combined with privacy and performance tools
Real-time protection: Yes
Current direct free-edition lab evidence: No, not in the cited 2026 report
Main limitation: Avira Web Protection is not part of the free antivirus

Avira Free Antivirus is available without charge for private, non-commercial home use. Avira’s own support documentation states that the free edition does not include the company’s Web Protection module.

This does not mean the product lacks real-time file protection. It means that an important paid browsing-protection component should not be listed as part of the free antivirus.

Avira also offers a separate free browser-safety extension, but that should be distinguished from the paid security suite’s integrated Web Protection.

Current testing caveat

AV-TEST’s April 2026 table lists Avira Internet Security, which received 6 points for protection, 5.5 for performance, and 6 for usability. It does not list Avira Free Security, so those exact numbers should not be assigned to the free edition.

Choose Avira when

• You value having several security, privacy, and performance tools in one application.
• You understand which features are free and which require payment.
• You are comfortable using a separate browser extension for additional browsing protection.

Skip it when

• You want a pure antivirus without utility or upgrade modules.
• Integrated free web protection is a priority.
• You require recent direct testing of the exact free edition.

Verdict: A useful free security bundle, but the lack of Avira’s integrated Web Protection and direct free-edition test evidence keeps it below the leading choices.

6. Panda Dome Free: Best for USB and rescue features

Best for: Users who frequently handle USB drives or want a rescue tool
Real-time protection: Yes
Current direct free-edition lab evidence: No, not in the cited 2026 reports
Main limitation: Less current independent evidence for the exact free edition

Panda’s current free product provides real-time protection, scheduled and manual scanning, automatic USB-drive scanning, a bootable rescue option, and a multimedia or game mode.

Those features make Panda interesting for users who exchange files on removable drives or want a recovery tool for a computer that cannot start normally.

Why Panda ranks lower

The AV-Comparatives report used here tested Panda Dome Advanced, not Panda Dome Free. The paid edition recorded a lower protection rate than the leading cluster and generated more false positives in that particular test. Those results are relevant to the vendor’s current technology but should not be copied directly onto the free edition.

Because the exact free edition lacks the same level of current public testing available for Defender, Avast, and AVG, Panda is a more conditional recommendation.

Verdict: Consider it for its USB and rescue features, but do not choose it solely on the assumption that paid-edition lab results describe the free product exactly.

Other active free antivirus products

ZoneAlarm Free Antivirus

ZoneAlarm currently advertises a free antivirus product for Windows 10 and Windows 11, and its release history shows continuing updates to the NextGen product line.

It has not been placed in the main six because the current broad independent evidence is less clear, and older compatibility discussions have raised questions about interaction with some Windows 11 security features. It deserves a fresh hands-on Raymond.CC test before receiving a strong recommendation.

Comodo Antivirus

Comodo still operates free antivirus pages, but its official compatibility information is inconsistent and commonly stops at Windows 10. Some download pages display strikingly old system requirements or release information.

That is not sufficient evidence for recommending it as a current Windows 11 product without original compatibility testing.

Kaspersky

Kaspersky may remain available in some countries, but it cannot be treated as a universal recommendation. The U.S. Department of Commerce prohibits Kaspersky from providing antivirus signature and codebase updates to U.S. customers and systems, with the relevant update restrictions having taken effect in September 2024.

U.S. readers should select another product. Availability, legal restrictions, and support differ elsewhere.

Free antivirus, free scanner, and free trial are not the same

A scanner that finds and removes malware after you manually launch it can be valuable, but it does not continuously inspect every new file and program.

Similarly, a “free download” button may lead to a paid suite with a 30-day trial. That product should not appear in a list of completely free antivirus programs unless a permanent free tier remains after the trial.

Free malware scanners for a second opinion

Malwarebytes Free

Malwarebytes Free scans and cleans malware already present on a Windows PC. Malwarebytes states that ongoing automatic and real-time protection belongs to Malwarebytes Premium.

That makes the free version useful as a second-opinion scanner, not a replacement for Defender or another real-time antivirus.

Best use: Run it when the primary antivirus reports nothing but the PC continues to show suspicious pop-ups, redirects, processes, or browser changes.

ESET Online Scanner

ESET Online Scanner is a free malware scanner that can run alongside an existing antivirus. ESET describes it as a free one-time check rather than continuous real-time protection.

Best use: Obtain an independent scan without replacing the current antivirus.

Microsoft Safety Scanner

Microsoft Safety Scanner is a downloadable tool designed to find and remove malware from Windows computers. It is started manually and should not be confused with Microsoft Defender’s ongoing real-time protection.

Download a fresh copy when needed because the scanner package is designed around current security intelligence.

Microsoft Defender Offline

Microsoft Defender Offline restarts the computer into a separate recovery environment before scanning. This can help when malware interferes with security software while normal Windows is running.

Open:

Windows Security > Virus & threat protection > Scan options > Microsoft Defender Antivirus (offline scan)

Save open work first because the computer will restart.

What happened to the antivirus programs in the original 2013 list?

The old article included more than 20 products, but retaining every name would make the new guide less accurate rather than more comprehensive.

Microsoft Security Essentials

Microsoft Security Essentials reached end of service on January 14, 2020 and is no longer available for download. Current Windows systems use Microsoft Defender Antivirus through the Windows Security interface.

FortiClient

FortiClient is now positioned around enterprise endpoint integration, secure access, and VPN functionality. Fortinet’s current download material describes the standalone tier around remote-access VPN rather than a permanent free consumer antivirus comparable to Defender or Avast.

ClamWin

ClamWin is an on-demand scanner rather than a complete always-on antivirus. Its own support community advises using a real-time antivirus as the primary protection and ClamWin as a backup scanner.

Ad-Aware, PC Tools, UnThreat, Outpost, and other legacy entries

These products are no longer appropriate recommendations for a modern Windows 11 guide. Their old screenshots, installer details, rankings, and download links should be removed rather than preserved for nostalgia.

A short update note can acknowledge that the page originally documented the much larger free-antivirus market of 2012 and 2013.

How to switch antivirus safely

1. Check the current provider

Open:

Windows Security > Virus & threat protection > Who’s protecting me? > Manage providers

Record which antivirus is currently active.

2. Download the new installer from the official site

Do not download an antivirus from a software mirror, advertisement, pop-up warning, or “premium crack” page.

Do not run the installer yet.

3. Uninstall the current third-party antivirus

Open:

Settings > Apps > Installed apps

Find the old antivirus and select Uninstall.

Use the vendor’s official removal tool when normal uninstallation fails or leaves services and drivers behind.

4. Restart Windows

A restart allows Windows to remove security drivers and normally reactivates Microsoft Defender while no other compatible provider is registered.

5. Confirm temporary protection

Open Windows Security and check that Defender is active before continuing.

6. Install the new antivirus

Run the official installer, review optional components, and avoid installing tools you do not need.

7. Update and scan

After installation:

1. Install all product updates.
2. Confirm that Windows Security recognizes the new provider.
3. Run the product’s initial scan.
4. Check that no previous antivirus services remain active.

Can two antivirus programs run together?

Do not run two full real-time antivirus products simultaneously unless both vendors explicitly document that configuration.

Possible consequences include:

• Both products scanning the same file
• Slower file access and application launches
• Competing quarantine actions
• Locked files
• Driver conflicts
• Installation or update failures
• One product mistaking another product’s activity for suspicious behavior

Windows reduces this problem by automatically disabling Microsoft Defender Antivirus when a compatible third-party antivirus registers correctly.

An intentionally compatible on-demand scanner is different. ESET Online Scanner, for example, is specifically described as being able to run alongside an existing antivirus.

A warning for Windows 10 users

Standard Windows 10 support ended on October 14, 2025. Unsupported installations no longer receive ordinary Windows security fixes, even though the computer and antivirus may continue operating. Microsoft recommends upgrading to Windows 11, replacing incompatible hardware, or enrolling eligible systems in Extended Security Updates.

The Consumer ESU program is available to eligible Windows 10 version 22H2 devices and can provide critical and important updates through October 12, 2027.

Antivirus software does not repair unpatched operating-system vulnerabilities. Installing Avast, Bitdefender, or another antivirus on unsupported Windows does not make the underlying operating system fully secure.

Frequently asked questions

What is the best completely free antivirus for Windows 11?

Microsoft Defender Antivirus is the best free option for most people. It is built into Windows, provides real-time protection, and achieved strong current independent results without requiring another installation.

Bitdefender Antivirus Free is the strongest focused third-party alternative, while Avast Free is the better choice for users prioritizing extra features and current direct testing of the free edition.

Is Microsoft Defender enough in 2026?

Yes, for many home users. It provides real-time and cloud-delivered protection and remains competitive in major independent tests. It should be combined with Windows updates, application updates, backups, secure passwords, multi-factor authentication, and cautious browsing.

Is Bitdefender Antivirus Free really free?

Yes. Bitdefender describes Antivirus Free as a permanent free product without hidden costs or a required trial. A Bitdefender Central account is required to install it.

Is Avast Free better than Microsoft Defender?

Not universally.

Avast offers more additional features and had a lower impact score than Defender in one current AV-Comparatives performance test. Defender, however, is integrated into Windows, produced no false positives in AV-Comparatives’ February to May real-world test, and does not require another security ecosystem.

Choose Avast for its extras and direct current free-edition evidence. Choose Defender for simplicity and integration.

Are Avast and AVG the same?

They are separate products, but AVG uses the Avast engine according to AV-Comparatives. Their current results are consequently very similar.

Do not install both.

Does Malwarebytes Free provide real-time protection?

No. Malwarebytes says its free product scans and cleans malware, while ongoing real-time protection is part of Malwarebytes Premium.

Can Malwarebytes Free run with Microsoft Defender?

Malwarebytes Free can be used as a manually started second-opinion scanner while Defender remains the real-time antivirus. Review the installation carefully because a premium trial or product setting may temporarily change how it registers with Windows.

Which free antivirus has the lowest system impact?

There is no universal winner for every computer.

In AV-Comparatives’ April 2026 test on its specified low-end Windows 11 system, Avast Free and AVG Free received a lower overall impact score than Microsoft Defender and the paid editions of Bitdefender and Panda. The lab explicitly says that results apply to the tested versions, hardware, and workloads and recommends trying the product on the user’s own system.

Is free antivirus safe?

A reputable free antivirus downloaded from its official vendor can provide legitimate protection. The major risks come from fake security pop-ups, unofficial installers, abandoned products, misleading trials, and programs with unclear support.

Download directly from Microsoft or the antivirus developer.

Why do antivirus companies offer free products?

A free antivirus can attract users to the vendor’s ecosystem. Companies may then promote paid features such as a VPN, identity monitoring, password management, cross-device coverage, advanced web protection, or technical support.

That business model does not automatically make the free antivirus ineffective, but the distinction between free and paid features should be clearly visible.

Can I install two free antivirus programs?

Do not install two full real-time antivirus programs. Use one primary antivirus and, when needed, a compatible on-demand scanner.

Is Kaspersky Free available in the United States?

Kaspersky cannot provide antivirus products, services, signature updates, or codebase updates to U.S. customers under current U.S. restrictions. U.S. users should choose another provider.

Can antivirus keep Windows 10 safe after support ends?

Antivirus can still detect malware, but it cannot provide missing Windows security patches. Upgrade to Windows 11, enroll an eligible computer in ESU, or move to supported hardware.

Should I pay for antivirus?

A paid product may be worthwhile when you need:

• Protection for several Windows, macOS, Android, or iOS devices
• Advanced family controls
• Identity monitoring
• A full VPN
• Central account management
• Enhanced web or email filtering
• Direct technical support
• Business or commercial licensing

Pay for features you actually need, not because the free product displays a warning beside every premium feature.

Final recommendation

Stay with Microsoft Defender Antivirus when you use Windows 11, keep the system updated, maintain backups, and do not need additional security utilities.

Choose Bitdefender Antivirus Free when you want a focused third-party antivirus and accept the account requirement.

Choose Avast Free Antivirus when current testing of the exact free edition and additional features matter more than its commercial interface and historical privacy issue.

Choose AVG AntiVirus Free instead of Avast when you prefer AVG’s interface, but do not treat the two as independent protection engines.

Consider Avira Free Security for its broader utility bundle and Panda Dome Free for its USB and rescue features, while recognizing that current public evidence for their exact free editions is more limited.

Keep Malwarebytes Free, ESET Online Scanner, or Microsoft Safety Scanner as second-opinion tools. They complement a primary antivirus but do not replace continuous protection.