WinHTTP Versions

Users of Microsoft Windows HTTP Services (WinHTTP) should use the latest version of the technology, version 5.1. Version 5.0 is no longer supported.

Version 5.1

WinHTTP 5.1 offers improvements over version 5.0; for more information about new features, see What's New in WinHTTP 5.1.

With version 5.1, WinHTTP is an operating-system component of the following operating systems:

  • Windows 2000, Service Pack 3 and later (except Datacenter Server)
  • Windows XP with Service Pack 1 (SP1) and later
  • Windows Server 2003 with Service Pack 1 (SP1) and later

For Windows Server 2003 with SP1, WinHTTP is a system side-by-side assembly. For more information, see Side-by-side Assemblies.

Redistribution of WinHTTP 5.1 outside of these operating systems is not supported.

Version 5.0

The WinHTTP 5.0 redistributable, "winhttp5.dll", runs on Windows 2000 or later, or Windows NT 4.0 with Microsoft Internet Explorer 5.01 or later.


The WinHTTP 5.0 download is no longer available. As of October 1, 2004, Microsoft has removed the WinHTTP 5.0 SDK download from MSDN and has terminated product support for version 5.0.