XeTeX (/ˈziːtɛx/ ZEE-tekhor /ˈziːtɛk/; see also Pronouncing and writing "TeX") is a TeX typesetting engine using Unicode and supporting modern font technologies such as OpenType, Graphite and Apple Advanced Typography (AAT). It was originally written by Jonathan Kew and is distributed under the X11 free software license.Initially developed for Mac OS X only, it is now available for all major platforms.