7 Best Free Antivirus Software for Windows and Mac (2026)

The best free antivirus for most people is the one already on their computer: Microsoft Defender on Windows and Apple’s built-in protection on a Mac. Free third-party tools such as Bitdefender Antivirus Free, Avast, AVG and Avira add extras, and a free on-demand scanner is handy for a second opinion. Here is what each free option really gives you, the catch with each, and how to choose.

Quick answer: On Windows 10 and 11, keep Microsoft Defender switched on and Windows updated; for most home users that is enough. If you want a different engine, Bitdefender Antivirus Free is the lightest third-party option with real-time protection. On a Mac, rely on macOS’s built-in XProtect and Gatekeeper and only install apps from the App Store or known developers. Keep Malwarebytes Free as a second-opinion scanner, not as your main protection.

Free antivirus software compared

Is Microsoft Defender enough?

For most home users, yes. Microsoft Defender Antivirus is built into Windows 10 and 11, turns on automatically when no other antivirus is installed, and updates through Windows Update. It gives real-time protection, cloud-based detection, ransomware protection through Controlled folder access, and SmartScreen warnings for dangerous downloads and websites. Microsoft explains each feature in its guide to the Windows Security app (external site).

Independent test labs such as AV-TEST (external site) and AV-Comparatives (external site) regularly test Defender alongside paid products, and you can check their latest results yourself before deciding. A third-party antivirus makes most sense if you want extra features (a password manager, VPN, identity monitoring or parental controls in one bundle) or if you manage a family’s PCs and want a single dashboard.

1. Microsoft Defender: best free antivirus for Windows

Defender costs nothing, uses no extra installer and stays out of the way. To check it, open Start > Settings > Privacy & security > Windows Security > Virus & threat protection. From there you can run a Quick, Full or Custom scan, or a Microsoft Defender Offline scan, which restarts the PC to catch malware that hides while Windows is running.

• Turn on Tamper Protection and Controlled folder access (ransomware protection) in the same screen.
• Keep Windows updated: security updates close the holes malware uses.

2. Bitdefender Antivirus Free: best lightweight alternative

Bitdefender Antivirus Free (external site) for Windows gives real-time protection, on-demand scans, behaviour-based detection and basic ransomware protection with no time limit. It needs a free Bitdefender Central account. The free version includes a basic VPN limited to 200 MB a day, and leaves out extras such as anti-tracking and automatic ransomware file recovery, which come with the paid Antivirus Plus.

Good to know: the free version is Windows only. If you install it, Windows turns Defender’s real-time scanning off automatically, which is normal.

3. Avast Free Antivirus: best for free extras

Avast Free Antivirus (external site) adds real-time protection plus tools such as a Wi-Fi network scanner and web protection, and has versions for Windows, Mac, Android and iPhone. Expect regular prompts to upgrade to paid products.

Privacy note: in 2024 the US Federal Trade Commission finalized an order (external site) requiring Avast to pay $16.5 million and banning it from selling or licensing web browsing data for advertising, over charges that it sold browsing data after claiming its products would block tracking. Read the privacy settings during setup and turn off any data-sharing options you don’t want.

4. AVG AntiVirus Free: best simple interface

AVG AntiVirus Free (external site) belongs to the same company as Avast (Gen Digital) and uses closely related protection technology, with a cleaner, simpler interface. It covers Windows, Mac, Android and iPhone. The same advice applies: decline extra software offers during installation and review the privacy options.

5. Avira Free Security: best free all-in-one bundle

Avira Free Security (external site) bundles antivirus with extras such as a limited VPN, a password manager and system tune-up tools, with apps for Windows, Mac, Android and iPhone. The bundle is generous, but several components exist to encourage an upgrade, so install only the parts you will use.

6. Malwarebytes Free: best second-opinion scanner

Malwarebytes is excellent at finding and removing adware, browser hijackers and other unwanted programs that some antivirus tools miss. According to Malwarebytes’ own comparison (external site), the free version includes on-demand scans but not real-time protection or web protection, which are paid. Use it alongside Defender when you suspect an infection, not instead of it.

7. XProtect and Gatekeeper: best free antivirus for Mac

Every Mac already has malware protection. Apple’s platform security guide (external site) explains its layers: Gatekeeper and notarization check apps before they run, XProtect detects and blocks known malware using signatures that Apple updates automatically, and macOS can remove malware it finds. There is nothing to install, but keep System Settings > General > Software Update > Automatic Updates turned on so security files stay current.

Most Mac infections come from pirated apps, fake “update your Flash or video player” pop-ups and fake security warnings. If you think your Mac is infected, follow our guide on how to remove malware from a Mac.

What about Kaspersky Free?

Kaspersky is no longer an option for US users. The US Commerce Department banned sales of Kaspersky antivirus software in the US in 2024, followed by a ban on its updates later that year, and Kaspersky closed its US business. Many US customers were moved to a different product, UltraAV. If Kaspersky is still installed on a US computer, it no longer gets updates, so replace it with Defender or another option on this list.

Free vs paid antivirus: what you give up

• Protection engine: free versions usually use the same core malware detection as the paid ones from the same company.
• Extras: paid suites add things like firewalls, full VPNs, identity theft monitoring, parental controls and support.
• Upsells: free tools pay for themselves with upgrade prompts, bundled offers and sometimes data collection. Read installer screens carefully.
• Licences: paid suites often cover several devices and phones in one plan. QOT’s older guides cover Norton’s free trial and tools and updating Norton for free if you already use it.

Which free antivirus should you choose?

• Most Windows users: Microsoft Defender, switched on and updated.
• Want a different engine on Windows: Bitdefender Antivirus Free.
• Want free extras and don’t mind prompts: Avast, AVG or Avira.
• Suspect an infection: run a Malwarebytes Free scan and a Microsoft Defender Offline scan.
• Mac users: built-in XProtect and Gatekeeper, plus safe download habits.

Only run one real-time antivirus at a time. Two real-time scanners can slow your PC and conflict with each other.

Free habits that matter more than any antivirus

1. Install updates for your operating system, browser and apps promptly.
2. Download software only from official sites or app stores.
3. Use a free password manager and turn on two-factor authentication for important accounts.
4. Ignore pop-ups that claim your device is infected and ask you to call a number or install a “cleaner”.
5. Back up important files, so ransomware can’t hold them hostage.

Phones need care too. See our guide on how to know if your phone is hacked.

FAQ

What is the best free antivirus for Windows 11?

Microsoft Defender, which is built into Windows 11, is the best starting point for most people. Bitdefender Antivirus Free is a good third-party alternative.

Is free antivirus safe to use?

Free antivirus from established companies is generally safe, but read the installer screens to avoid bundled offers, and check the privacy settings for data sharing.

Do Macs need antivirus?

Macs have built-in malware protection (XProtect and Gatekeeper). Most users don’t need extra antivirus if they keep macOS updated and avoid pirated or unknown apps.

Is Windows Defender better than Avast?

Both give real-time protection. Defender is built in with no ads or upgrade prompts, while Avast adds extra free tools. Check recent AV-TEST or AV-Comparatives results to compare detection.

Can I use two antivirus programs at once?

Not two real-time scanners. You can, however, keep one real-time antivirus and occasionally run an on-demand scanner such as Malwarebytes Free.