What are some alternatives?
When comparing Free YouTube to MP3 Converter and youtube-dl, you can also consider the following products
yt2mp3.org - Free online YouTube to MP3 Converter
Youtube-DLG - A cross platform front-end GUI of the popular youtube-dl written in wxPython.
Point MP3 - Pointmp3 is one of the best and an easiest online tool that helps you to converts your favourite tracks on YouTube to the mp3 format that is of the highest quality.
4k Video Downloader - 4K Video Downloader is a software program that helps people download video files from sites such as Facebook, YouTube and Dailymotion.
Peggo.tv - Peggo is a free YouTube to mp3 converter online.
Video DownloadHelper - DownloadHelper is a tool for web content extraction.