A web desktop or webtop is a desktop environment embedded in a web browser or similar client application. A webtop integrates web applications, web services, client–server applications, application servers, and applications on the local client into a desktop environment using the desktop metaphor. Web desktops provide an environment similar to that of Windows, Mac, or a graphical user interface on Unix and Linux systems. It is a virtual desktop running in a web browser. In a webtop the applications, data, files, configuration, settings, and access privileges reside remotely over the network. Much of the computing takes place remotely. The browser is primarily used for display and input purposes.

The terms "web desktop" and "webtop" are distinct from web operating system, a network operating system such as TinyOS or distributed operating system such as Inferno. In popular use, web desktops are sometimes referred to incorrectly as web operating systems or simply WebOS.

In the context of a web desktop, the term Webtop was first introduced by the Santa Cruz Operation (SCO) in 1994 for a web-based interface to their Unix operating system. This application was based on the provisional application entitled "The Adaptive Internet Protocol System" filed Nov. 13, 1997, serial number 60/065,521 and is the U.S. patent for the technology used in the Tarantella Webtop. Andy Bovingdon and Ronald Joe Record, who both explored the concepts in different directions, are often credited as the inventors. The initial SCO Webtop, developed by Record, utilized a Netscape Navigator plugin to display applications in a browser window via TightVNC. A trademark application for "SCO Webtop" was filed with the U.S. Patent and Trademark Office on November 8, 1996. In order to avoid confusion with the more complex technology incorporated into the Tarantella Webtop it was abandoned on December 24, 1997 by The Santa Cruz Operation.