https://mp3juice.tv/ (Search the YouTube video or paste the link. Ads included.)
https://www.mp3converter.net/ (Paste your YouTube link. Ads included.)
http://www.listentoyoutube.com/ (Have to click dowload a couple of times. Ads included.)
https://www.mp3juices.cc/ (Doesn't work on some school WIFI's so you have to connect to a WIFI network that is not from school. Ads rarely pop up. )
https://mp3-youtube.download/en (Paste your YouTube link. Ads included.)
Ads may pop up in a new tab but just go back to the original tab then you are good to download the music.