Do I need extra antivirus if Defender is on?

Microsoft Defender Antivirus is built into Windows and is a free baseline. The third-party suites here add VPNs, scam protection and identity tools, which the built-in version does not include.

Which antivirus has a free version?

Avast offers Free Antivirus for PC, Bitdefender offers a free Antivirus version, Malwarebytes has a free malware scan and cleaners, and Avira offers Avira Free Security for Windows. Norton and ESET have trials but no free antivirus.

Which antivirus is open source?

ClamAV is open source under GPL-2.0 and is an engine for mail servers, Linux and developers. The other products here do not describe their software as open source on their sites.

Which antivirus covers the most platforms?

Bitdefender, Malwarebytes, Avira and Norton each list Windows, macOS, Android and iOS. Avast, Trend Micro, F-Secure and Webroot also cover Windows, Mac and phones. ESET lists Windows, macOS, Android and Linux, and Microsoft Defender covers Windows only.

Best Antivirus Software in 2026: Top 11 Ranked

The ranking

Top pickBitdefender90.5
Best with a free planMicrosoft Defender Antivirus89.0
Best open sourceClamAV78.5

1
Bitdefender
A free Antivirus version and paid suites that cover five devices per account, with VPN and identity tools bundled. Its many product tiers make the right plan harder to pick.
Best for Multi-device protection with a free starter
WindowsmacOSAndroidiOSFree plan, paid upgrades
90.5of 100
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2
Microsoft Defender Antivirus
Built into Windows Security at no extra cost and needs no setup. It covers Windows only, and tools such as a VPN come from third-party suites like the ones in this list.
Best for Windows PCs that need no extra software
WindowsFree
89.0of 100
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3
Malwarebytes
A free malware scanner and device cleaners, with paid Premium Security for ongoing protection, a VPN and a browser guard. It covers PCs, Macs, Android and iPhone with a 60-day money-back guarantee.
Best for Free malware scans and paid ongoing protection
WindowsmacOSAndroidiOSFree plan, paid upgrades
87.0of 100
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4
ESET
Antivirus for Windows, macOS, Android and Linux with anti-phishing and Wi-Fi protection, sold as subscriptions after a 30-day trial. It has no free version after the trial and lists no iOS app.
Best for Subscription antivirus for Windows and Mac
WindowsmacOSAndroidLinuxSubscription
85.5of 100
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5
Avast
Its free tier covers PC, Mac and mobile, which Avira's free download does not, and the paid tiers add a VPN and identity tools. Norton and ESET offer no free antivirus after their trials.
Best for Free protection on PC and Mac with an upgrade path
WindowsmacOSAndroidiOSFree plan, paid upgrades
82.5of 100
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6
Norton
Antivirus bundled with a VPN, scam protection and LifeLock identity options, with mobile apps for Android and iOS. It has no free antivirus, and first-year discounts renew at a higher price.
Best for Antivirus bundled with VPN and identity tools
WindowsmacOSAndroidiOSSubscription
81.0of 100
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7
Avira
Free Avira Free Security for Windows, with paid Prime plans that include Prime Mobile apps for iOS and Android. The free download is listed for Windows only.
Best for Free Windows antivirus with paid mobile plans
WindowsmacOSAndroidiOSFree plan, paid upgrades
80.0of 100
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8
Trend Micro
Covers Windows, Mac, Android, iOS and Chromebook, and its top suite includes a password manager. Unlike Norton, which bundles a VPN, Trend Micro sells its VPN as a separate product and has no free antivirus.
Best for Households with several platforms and a paid suite
WindowsmacOSAndroidiOSChromeOSSubscription
79.5of 100
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9
ClamAV
An open-source GPL-2.0 antivirus engine for Windows, macOS and Linux, suited to administrators, mail gateways and developers. It has no interface of its own and is not a consumer app.
Best for Open-source scanning for servers and mail
WindowsmacOSLinuxFree and open sourceOpen source
78.5of 100
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10
F-Secure
Covers Windows, macOS, iOS and Android with a free trial, and its VPN and identity tools are separate products. It has no free antivirus after the trial, and its platform list is shorter than Trend Micro's.
Best for Subscription buyers who want a free trial first
WindowsmacOSiOSAndroidSubscription
77.5of 100
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11
Webroot
Cloud-based antivirus for PCs, Macs, phones and Chromebooks, with identity, VPN and password tools in its bundles. Free trials are offered, but there is no free antivirus, and some features work only on iOS and Android.
Best for Families who want one subscription across devices
WindowsmacOSAndroidiOSChromeOSSubscription
75.5of 100
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At a glance

Product	Score	Price	Platforms	Free version	Extra tools
Bitdefender	90.5	Free plan, paid upgrades	WindowsmacOSAndroidiOS	Yes	VPN, identity protection, scam tools
Microsoft Defender Antivirus	89.0	Free	Windows	Yes	Personal subscription for other devices
Malwarebytes	87.0	Free plan, paid upgrades	WindowsmacOSAndroidiOS	Yes	VPN, browser guard, cleaners
ESET	85.5	Subscription	WindowsmacOSAndroidLinux	No	Anti-phishing, Wi-Fi protection, VPN
Avast	82.5	Free plan, paid upgrades	WindowsmacOSAndroidiOS	Yes	VPN and identity tools in paid tiers
Norton	81.0	Subscription	WindowsmacOSAndroidiOS	No	VPN, scam protection, LifeLock
Avira	80.0	Free plan, paid upgrades	WindowsmacOSAndroidiOS	Yes	Paid Prime plans
Trend Micro	79.5	Subscription	WindowsmacOSAndroidiOSChromeOS	No	Passwords in top suite; VPN sold separately
ClamAV	78.5	Free and open source	WindowsmacOSLinux	Yes	None; engine only
F-Secure	77.5	Subscription	WindowsmacOSiOSAndroid	No	VPN, ID and scam protection products
Webroot	75.5	Subscription	WindowsmacOSAndroidiOSChromeOS	No	Identity, VPN, password manager, cloud storage

How to choose antivirus software

Already on Windows: Microsoft Defender is built into Windows Security and needs no extra install, so it is the baseline to compare against.
Free versus paid: Bitdefender and Malwarebytes have free versions; Avira's free download is Windows only; ESET and Norton are paid after a trial.
Devices per account: Bitdefender's suites cover up to five devices, so check the device count on any paid plan before you buy.
Extra tools: VPNs, scam protection and identity tools come with paid suites from Bitdefender, Malwarebytes, Norton and ESET, not with the built-in or free versions.

What the scores weigh

Malware protection coverage
Free version and price
Platform coverage
Extra tools such as VPN and identity
Open source and transparency

Scores are editorial, from 0 to 100, and use these criteria. Full method · Disclosure

About antivirus software

Antivirus products fall into three groups. Microsoft Defender comes built into Windows. Bitdefender, Malwarebytes, Norton, ESET and Avira sell antivirus in paid suites, and some also offer a free version. ClamAV is an open-source engine for mail servers, Linux and developers, not a consumer app.

Free versions are narrow here. Microsoft Defender is included with Windows, Avast offers Free Antivirus for PC, Bitdefender offers a free Antivirus version, Malwarebytes has a free scan and cleaners, and Avira's free download is listed for Windows only. Norton and ESET have no free antivirus after their trials. Extra tools such as VPNs, scam protection and identity monitoring come with the paid suites, not the free versions.

Coverage matters too. Bitdefender, Malwarebytes, Avira and Norton list Windows, macOS, Android and iOS, and ESET lists Windows, macOS, Android and Linux. Microsoft Defender covers Windows only, and ClamAV covers Windows, macOS and Linux as an engine. The scores are editorial judgments against the criteria, not results from independent lab tests.

Frequently asked questions

Do I need extra antivirus if Defender is on?: Microsoft Defender Antivirus is built into Windows and is a free baseline. The third-party suites here add VPNs, scam protection and identity tools, which the built-in version does not include.
Which antivirus has a free version?: Avast offers Free Antivirus for PC, Bitdefender offers a free Antivirus version, Malwarebytes has a free malware scan and cleaners, and Avira offers Avira Free Security for Windows. Norton and ESET have trials but no free antivirus.
Which antivirus is open source?: ClamAV is open source under GPL-2.0 and is an engine for mail servers, Linux and developers. The other products here do not describe their software as open source on their sites.
Which antivirus covers the most platforms?: Bitdefender, Malwarebytes, Avira and Norton each list Windows, macOS, Android and iOS. Avast, Trend Micro, F-Secure and Webroot also cover Windows, Mac and phones. ESET lists Windows, macOS, Android and Linux, and Microsoft Defender covers Windows only.