Web clients only provide a web browser, and rely on web applications to provide general-purpose computing functionality. However, note that web applications may use web storage to store some data locally, e.g. for "offline mode", and they can perform significant processing tasks as well. Rich Internet Applications for instance may cross the boundary, and HTML5 Web Applications can leverage browsers as run-time environments through the use of a cache manifest or so called "packaged apps" (in Firefox OS and Chrome).
Examples of web thin clients include Chromebooks and Chromeboxes (which run Chrome OS) and phones running Firefox OS.
Chromebooks and Chromeboxes also have the capability of remote desktop using the free Chrome Remote Desktop browser extension, which means, other than being a web thin client, they can also be used as an ultra-thin client (see above) to access PC or Mac applications that do not run on the Chromebook directly. Indeed, they can be used as a web thin client and an ultra-thin-client simultaneously, with the user switching between web browser and PC or Mac application windows with a click.
Chromebooks are also able to store user documents locally – though, with the exception of media files (which have a dedicated player application to play them), all such files can only be opened and processed with web applications, since traditional desktop applications cannot be installed in Chrome OS.