Microsoft Admits Windows 11 Runs on 30-Year-Old Code Designed for Windows 95

Breaking News – Microsoft has acknowledged that Windows 11 still relies on core code written in the 1990s, despite marketing the operating system as the most modern and secure version of Windows ever.

Mark Russinovich, Chief Technology Officer of Microsoft Azure and founder of Sysinternals, revealed in a video posted by the Microsoft Dev Docs account that the Win32 API – a fundamental layer of Windows – was designed for Windows 95 and remains a first-class surface in 2026.

“Did anyone in the 90s expect Win32 to still be a first-class API surface in the year 2026? And I think I can safely answer, ‘No.’ Nobody, I think, would’ve expected that because we were thinking flying cars and moon stations by the year 2026. Not Win32 that was designed back in Windows 95 days,” Russinovich said.

Background: Why Old Code Persists

The Win32 API became widespread with Windows 95 but had already been implemented in Windows NT. Microsoft never planned for it to remain relevant for decades.

Russinovich explained that the API’s staying power stems from its role as the “bedrock” of Windows, with countless apps, technologies, and ecosystems built on top of it. “It’s kind of bedrock,” he added.

Previous attempts to replace Win32, such as WinRT, failed to achieve full adoption, leaving a gap between traditional desktop apps, Win32, and the browser-based HTML/JavaScript ecosystem.

What This Means for Windows 11 Users

While Windows 11 features modern security updates and a polished interface, its core remains anchored to legacy code from the 1990s. This ensures backward compatibility with millions of existing applications but also means potential security risks and technical debt.

Microsoft has not announced plans to replace Win32 entirely, but the admission highlights the challenges of modernizing a platform with decades of accumulated history.

Russinovich also noted that other tools from the same era, including Sysinternals, Sysmon, and ZoomIt, continue to be essential. Learn more about Sysinternals below.

Sysinternals: Another 1990s Relic Still Used Today

Sysinternals, a suite of system utilities first released in the 1990s, is still widely used for Windows troubleshooting. Microsoft has even begun integrating Sysmon directly into Windows.

The company continues to support these tools as they provide deep visibility into system behavior, something modern tools have not fully replaced.

For more details, see the original Microsoft Dev Docs post.