This is a helper app for the game Dungeons, Dice & Danger by Richard Garfield.
It allows multiple users to connect to a shared session where dice can be rolled and options can be presented representing all the different combinations that can be made with these dice. It shows a separate section for whomever can/wants to use the black die as well. You can also highlight certain numbers to get an idea of what other combinations use them.
The app can be found at: rab.gg/dungeons-dice-danger-helper