Download music from Youtube to Android or iPhone - Trenovision
Top 10 Sites to Convert YouTube to MP3
GitHub - AddonDeveloper/youtube-to-mp3-userscript: The 320 kbps YouTube mp3 userscript generates a 320 kbps - MP3 DOWNLOAD button on YouTube.com. Convert YouTube to mp3 and download the file to your device.
拡張機能「 Youtube Downloader」 - Opera アドオン
YouTube to Mp3 Converter — Convert YT to MP3 | by Rahmanahmadcomputer | Medium