We are currently testing HTTP/3 support in IIS/http.sys internally. Cannot comment on any external product release timelines.

You mean IIS? HTTP.SYS isn't a webserver.

HTTP.SYS is the core of a Windows NT native web server; the async listen/accept loop, IOCP-based data transfer, etc. IIS is built on top of HTTP.SYS. I presume that it ships with Windows for ease of servicing; it is after all a kernel-mode driver (of sorts).

The kernel module HTTP.SYS contains a HTTP server. It's used by IIS, but you can also use its API directly.

Wow, didn't know that.

API for the curious: https://docs.microsoft.com/en-us/windows/win32/http/http-api...