Rainbow Piano App is an interactive virtual piano that generates musical tones through a Web Audio API, playable via mouse clicks, touch events, or computer keyboard mappings. The visualization presents a gradient-styled keyboard with animated key presses, where white keys respond to letter keys A through semicolon and black keys map to W, E, T, Y, U, O, and P. A demo melody button triggers a pre-recorded sequence. The interface uses DOM manipulation with CSS transitions for a smooth, responsive design across different screen sizes.