This is a visual tool designed to help you understand key signatures.
Start by selecting the major key to look at. Then you can also select a different major key to compare it against.
Selecting a mode will display the chords in that mode and their roman numerals. Clicking on a chord will highlight the chord tones in the below scales.
All of the notes and their proper names of the first selected scale will be displayed under the "Notes" header
Below this the two scales are displayed on the chomatic line. Scrolling left to write will change the mode displayed, allowing you to easily compare them.