Files can be accessed directly like so:

https://ledlamp.github.io/piano-sounds/GreatAndSoftPiano/a0.mp3

Most of these sounds came from electrashave's server at http://files.meowbin.com/Sounds. GreatAndSoftPiano, HardAndToughPiano, and LoudAndProudPiano were obtained from Yoshify by FireController1847. `info.json`'s for those were presumably made by Charsy. Emotional 2.0 originated from www.multiplayerpiano.com but was downloaded from charsy.meowbin.com.