HarfBuzz (loose Latin transliteration of Persian: حرفباز, "Opentype") is a software development library for shaping of Unicode text. The most recent incarnation of HarfBuzz ("New HarfBuzz") targets various font technologies while the first version ("Old HarfBuzz") targeted only OpenType fonts. New HarfBuzz provides only text shaping functionality and not text layout or rendering, which require other libraries. Pango (which incorporates HarfBuzz) can be used for higher-level text layout, and FreeType or Anti-Grain Geometry for text rendering.
The goals for New HarfBuzz, as set by the developers, are for HarfBuzz to be beautiful, robust, flexible, efficient, and portable. Some potential applications that are a good-fit for HarfBuzz are: GUI toolkits, web browsers, word processors, designer tools, font design tools, terminal emulators, batch document processors, and TeX engines.
HarfBuzz evolved from code that was originally part of the FreeType project. It was then developed separately in Qt and Pango. Then it was merged back into a common repository with an MIT license. This was Old HarfBuzz. Old HarfBuzz is no longer being developed, as the path going forward is New HarfBuzz.