Microsoft CTO confesses that 30-year-old code from the mid-90s still forms the bedrock of Windows 11 — ancient Win32 API still the backbone, but CTO says it's 'more relevant than ever in 2026'

Microsoft CTO Mark Russinovich said Windows 11 still depends heavily on Win32 code dating back to the mid-1990s.

He said the legacy persists because countless apps and Microsoft technologies were built on top of it.

The comments highlight how deeply older Windows code is embedded in modern Microsoft software.

That helps explain why Microsoft can’t easily replace Win32, even while pushing for better performance and reliability.