Windows Sysinternals is a part of the Microsoft TechNet website which offers technical resources and utilities to manage, diagnose, troubleshoot, and monitor a Microsoft Windows environment. Originally, the Sysinternals website (formerly known as ntinternals) was created in 1996 and was operated by the company Winternals Software LP, which was located in Austin, Texas. It was started by software developers Bryce Cogswell and Mark Russinovich.Microsoft acquired Winternals and its assets on July 18, 2006.

The website featured several freeware tools to administer and monitor computers running Microsoft Windows. The software can now be found at Microsoft. The company also sold data recovery utilities and professional editions of their freeware tools.

Winternals Software LP was founded by Bryce Cogswell and Mark Russinovich, who sparked the 2005 Sony BMG CD copy protection scandal in an October 2005 posting to the Sysinternals blog.

On July 18, 2006, Microsoft Corporation acquired the company and its assets. Russinovich explained that Sysinternals will remain active until Microsoft agrees on a method of distributing the tools provided there. However, NT Locksmith, a Windows password recovery utility, was immediately removed.^{[citation needed]} Currently, the Sysinternals website is moved to the Windows Sysinternals website and is a part of Microsoft TechNet.

Mark E. Russinovich (born c. 1966) is a Technical Fellow in the Platform and Services Division at Microsoft. He was a cofounder of software producers Winternals before it was acquired by Microsoft in 2006.

He was born in Salamanca, Spain and was raised in Birmingham, Alabama, until he was 15, when he moved with his family to Pittsburgh, Pennsylvania. His father was a radiologist and his mother was a business administrator of his father's radiology practice in Pittsburgh.

He was introduced to computers when his friend's father got an Apple II in 1970s. He was able to reverse engineer its ROM and write programs for it. At age 15, he bought himself his first computer, a TI99/4A. About six months later his parents bought him an Apple II+ from his local high school when it upgraded the computer labs to Apple IIe's. He also wrote magazine articles about Apple II.

In 1989, Russinovich earned his B.S. in computer engineering from Carnegie Mellon University. The following year he received an M.S. in computer engineering from Rensselaer Polytechnic Institute. He later returned to Carnegie Mellon, where he received a Ph.D. in computer engineering in 1994.