I used to only have Chrome to use an extension which does the same thing. Super happy to finally leave that behind because this exists.

Finally, a pitch shifter on Firefox that doesn't severely reduce the sound quality

It works on android which is awesome! The semitones are inaccurate. I'm not 100% what the error is but it seems 12 semitones in the app = 5 semitones IRL.

Es justo lo que necesitaba. Hasta ahora no había ninguna alternativa funcional a la extensión "Trasposer" de Chrome para Firefox. Me gustaría que también funcionara con Spotify. Gracias :)