Download of HPLF 2.0.3 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The following version: 2.0 was the most frequently downloaded one by the program users.
The program's installation file is generally known as HPLF-MAC.zip. The actual developer of this Mac application is H-Pi Instruments. The program lies within Audio & Video Tools, more precisely Music Production. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
H-Pi Lo-Fi Microstudio (HPLF) is a stand-alone [not a plugin] fully tunable softsynth and multi-track audio utility which places emphasis first on tuning flexibility, using basic building blocks of electronic sound. Tunings can be specified across the entire MIDI range (unique tunings per channel, totaling 2048 available pitches).
You may want to check out more Mac applications, such as M-Audio Key Rig, which might be similar to HPLF.