XQuartz

About

XQuartz is an open-source project that develops a version of the X.Org X Window System for macOS. Together with supporting libraries and applications, it forms X11.app, which Apple shipped with OS X versions 10.5 through 10.7.

XQuartz is available as downloads for several macOS versions. The current release, 2.8.6, supports macOS 10.13 or later, and earlier releases support OS X 10.9, 10.6.3, and 10.5 (Leopard). Leopard users are advised to reinstall the latest XQuartz X11 release after applying a system software update, because Apple's update can overwrite the XQuartz package and cause conflicts.

An XQuartz installation consists of many individual pieces of software, each with its own license. The X.Org components are covered by the X.Org Foundation licenses, and the quartz-wm window manager included in the distribution uses the Apple Public Source License Version 2.