KeyboardTools is a multi-platform application for Piano and Keyboard Players of any style, helps you finding scales, chords, voicing, harmony and practicing. It comes with a bunch of useful features and customization : from 2 to 5 octaves, different piano sounds, metronome, favorites tunes, circle of fifths, chords and scales, printing and copying the keyboard, ...
The keyboard can show notes, key numbers, can begin from midi note C-1 to C2, and will respond to mouse click, handling velocity, etc. Several windows can be opened, for example, one showing a chord and another showing the relative scale. The favorites tunes "Player" can play almost any video or sound files.

The license of this software is Free Trial Software, the price is $9.99, you can free download and get a free trial.