MediaHuman YouTube To MP3 Converter Extracts MP3 audio from YouTube, Vimeo, Dailymotion and SoundCloud.

Youtube Video and Audio Downloader is an open-source project, downloading Youtube videos.

Easy Youtube Video Downloader is a cross-browser, cross-platform and free web-browser add-on to perform conversion on external servers.

SYLoader is a simple, fast Youtube downloader.

ClipGrab is a multi-platform software for downloading videos from popular websites such as YouTube, Vimeo, Dailymotion or Metacafe.

Youtube-DLG is a cross platform front-end GUI of the popular youtube-dl written in wxPython.

4K YouTube to MP3 was specifically created to extract audio from YouTube, Vimeo or Facebook and save it in MP3, M4A, OGG.