This app transposes files from the free karaoke game UltraStar Deluxe to GW2 sheet music.
For each note in a song, the karaoke files contain the number of semitones between C and that note. Each octave of the Western chromatic scale has 12 semitones, but in GW2, you can only play 7 notes per octave (on some instruments, the eigth note is the lowest note from the next octave), just like playing a piano with only the white keys. Most songs also use only 7 notes per octave and the process of transposition shifts the song by a certain number of semitones to fit your 7 tones in GW2, as the numbers of semitones between the used notes usually follow a certain pattern (called a musical scale, e.g. the major or the Dorian scale) and if you are playing your instrument alone, only the semitone steps between the notes count for the melody but not the actual notes.
There are tens of thousands of songs in the UltraStar database. A registration is required. Do not use any sensitive passwords there, as the site is known to have serious security issues.
There are songs in which the melody does not primarily come from the vocals. These do not work, as the karaoke files contain only the notes of the vocals.
Transposed from with unplayable notes and octave changes.