My Fave FFT App
Its fast/slow and window choices, and look and feel are very natural for working in the frequency domain.
Watching music it just "looks" proper.
The ability to decode the frequency peak to a musical note is a natural, but extremely useful feature...
Three features Id like to see?
1) Screen capture video... share the look of your favorites dynamically.
2) Capture-Process-Slomo: capture a length of audio, process the FFT, then play the video back slowly, with scrubbing, to allow transposition of complex arpeggios...
3) Transpose 2) into musical score or tablature.
Capn Zig about
FFT Plot, v1.2.1