Our website provides a free download of PHD2 2.5.0 for Mac. The actual developer of this free software for Mac is Open PHD2 Guiding. The application lies within System Tools, more precisely Device Assistants.
From the developer:
PHD2 is telescope guiding software that simplifies the process of tracking a guide star, letting you concentrate on other aspects of deep-sky imaging or spectroscopy.
You may want to check out more software for Mac, such as ToFi, QuakeBar or iStar Composer, which might be related to PHD2.