Phattr is an easy online service for converting videos to MP3. The service is free so you don't need an account. The only thing you need is a YouTube URL. We will start to convert the audio track of your video file to MP3 as soon as you have submitted it and you will be able to download it. Our software is platform independent so you can use it with macOS, Linux, Windows, Android, Windows Phone and iOS. All our conversions will be perfomed in high quality mode with a bitrate of 320 kBit/s. We need approximately at least 1 minute per video.
The YouTube-MP3 official website.