Harmonic was a sort of pet project, built on-and-off over several years by Wil Gieseler (supapuerco on GitHub) through Mindquirk. After Wil closed Mindquirk, he gently opened his code for We the People to maintain it if possible.
Matti Schneider-Ghibaudo then updated it when iTunes 10 broke compatibility, and is its on-and-off maintainer since he published his fork as the update stream in services like iUseThis.
kawazoe fixed important crashes and leaks in the Objective-C plugin.