Drop an MP3 or WAV and get it back retuned to A = 432 Hz. Everything happens in your browser: your files never leave your device.
Most music is tuned with the note A at 440 Hz. Converting to 432 Hz lowers the whole track by 31.77 cents, a little less than a third of a semitone, so A lands on 432 Hz.
No. Decoding, retuning and encoding all run inside your browser. Nothing is sent to a server.
Yes, slightly. Tune432 retunes like a turntable running a bit slower: pitch and tempo drop together by about 1.8%. This keeps the sound clean with no stretching artifacts.
It tunes the track so that C5 sits at 528 Hz, which puts A at 444 Hz. It raises the track by about 15.67 cents.
There is no solid scientific evidence for health effects. Many listeners simply prefer the warmer, lower sound. Tune432 is a listening tool, not a medical one.