Do you still need third-party antivirus on your Windows PC?

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Last April, someone at Microsoft published a document on the Windows Learning Center that made a thoroughly uncontroversial claim: "For many Windows 11 users, Microsoft Defender Antivirus covers everyday risk without requiring additional software. The choice to add third‑party antivirus depends on how you use your PC and which features you value."

The article drove a flurry of coverage from tech blogs , but the hullabaloo died down in a few days.

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And then, a month or so later, the article disappeared in a puff of virtual smoke. It vanished without a trace, a note, or an explanation, with the former link redirecting to the Windows Learning Center home page.

Fortunately, Microsoft couldn't scrub the page from the Internet Archive, which still has a mirror of the original content .

Microsoft deleted this post, but the advice is uncontroversial and still accurate.

As far as I can tell, Microsoft has never publicly addressed the reasons why the post was removed. (I've asked the company for comment and will update this post if I hear back.) If I had to guess, I would suspect howls of protest and accompanying threats of antitrust complaints from the third-party security industry had something to do with it.

How big is the consumer security software market? A pricey and proprietary Security Products Tracker from IDC reportedly pegged "endpoint security revenues" at $21.6 billion, "divided between the Modern Endpoint and Consumer Digital Life Protection secondary markets." That's a lot of market to defend.

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But the debate raises a legitimate question: Is Microsoft Defender, in combination with the rest of the security tools in Windows 11 , good enough for most consumers and small businesses? Is there still a case to be made for third-party software?

The trouble with researching security software is that there are few truly independent, reliable sources of information. Some of the larger players, including CrowdStrike, Palo Alto Networks, Cisco's Talos division, Mandiant (now part of Google), and Microsoft, release thorough reports on the threat landscape that mainly focus on securing enterprise networks.

Those reports often take a cursory swipe at the state of unmanaged devices, but that's not their main focus.