Harfbuzz began its life as text shaping code within the FreeType project, (and you will see references to the FreeType authors within the source code copyright declarations) but was then abstracted out to its own project. This project is maintained by Behdad Esfahbod, and named Harfbuzz. Originally, it was a shaping engine for OpenType fonts - "Harfbuzz" is the Persian for "open type".