HarfBuzz

HarfBuzz is an OpenType text shaping engine.

The current HarfBuzz codebase, formerly known as harfbuzz-ng, is versioned 1.x.x and is stable and under active maintenance. This is what is used in latest versions of Firefox, GNOME, ChromeOS, Chrome, LibreOffice, XeTeX, Android, and KDE, among other places. The canonical source tree is available here. Also available on github. See Download for release tarballs.

The old HarfBuzz codebase, these days known as harfbuzz-old, was derived from FreeType, Pango, and Qt and is available here. It is not actively developed or maintained, and is extremely buggy. All users are encouraged to switch over to the new HarfBuzz as soon as possible. There are no release tarballs of old HarfBuzz whatsoever.