Open Source PHP webOS: Lucid Desktop
Web-based operating systems are becoming more and more solid everyday (thanks to JS frameworks that offer a desktop-like experience).
They are mostly hosted web applications which is not surprising. However, Lucid Desktop is an open source webOS that is built with PHP and uses a SQL database for storing data.
It is a multi-user application which is very modular with the support for installable applications.
Lucid Desktop already comes with lots of applications like text editor, calculator, image viewer, simple games, web browser, feed reader, music player and more.
With the help of a file manager, you can add-edit-delete files and folders (a context menu makes these steps easier), change the appearance of the desktop with theming support and auto-update the OS to the latest version.
Compatibility: All Major Browsers