A free, open-source browser extension called Karaoke Pitch that lets you adjust the pitch of a YouTube video (and optionally store that chosen pitch for later).

I find it to be a great way to practice singing/music.

Firefox: https://addons.mozilla.org/en-US/firefox/addon/karaoke-pitch...

Chrome: https://chromewebstore.google.com/detail/karaoke-pitch/facck...

https://github.com/djeastm/karaoke-pitch

The Firefox one has 40 average daily users and the Chrome one has 287 installs as of today.

There was a big jump in late October that might have had something to do with Halloween? I have no idea if people do karaoke more on Halloween. Still no ratings yet for either version, but maybe someday someone will.