CONV. - Convert YouTube video to MP3, GIF or MP4
MediaHuman YouTube to MP3 Converter - Extracts MP3 audio from YouTube, Vimeo, Dailymotion, Mixcloud, Bandcamp, SoundCloud and many others. Available for macOS, Windows and Ubuntu/Linux. FREE!
Downie - Video download for OS X. Downie supports at this moment over 1,000 different sites.
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.
Yout - YouTube to Mp3 Converter
4k Video Downloader - 4K Video Downloader is a software program that helps people download video files from sites such as Facebook, YouTube and Dailymotion.