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!
2conv.com - 2conv.com is a simple yet powerful online video converter and downloader that allows you to download any YouTube videos in Mp3 quickly.
Youtube Video and Audio Downloader - Download YouTube videos in all available formats and extract the original audio files.
KlickAud - Klickaud is a free web-based application to online download SoundCloud track, music, songs in MP3 formats.
4k Video Downloader - 4K Video Downloader is a software program that helps people download video files from sites such as Facebook, YouTube and Dailymotion.
SoundCloud to MP3 - SoundCloudToMP3.me is a great online service for downloading and converting soundcloud to MP3 files.