XQuartz

XQuartz provides an implementation of the X.Org X Window System that runs on macOS, delivering the X11 environment and supporting libraries needed to run graphical X applications on Apple’s desktop operating system. It packages the X server, client libraries, and the quartz‑wm window manager into the X11.app bundle, allowing users to launch and interact with software that depends on the X11 protocol.

The project targets macOS users who require compatibility with legacy or cross‑platform X applications, especially on versions from 10.5 onward. By supplying a maintained, open‑source X11 implementation, it fills the gap left after Apple ceased shipping its own X11 package, and it can be reinstalled after system updates to avoid conflicts.

XQuartz is distributed under multiple open‑source licenses, with the core X.Org components following the X.Org Foundation terms and the quartz‑wm manager using the Apple Public Source License Version 2. The software is considered stable and is available for download in package form for recent macOS releases.