Pros of Airy: Straightforward and easy to use. Then, choose the MP3 format from the dropdown menu to begin your download. The interface is very simple: Just copy and paste the URL from the YouTube video you wish to convert. When you run Airy for the first time, you will be prompted to use your YouTube account to login, or you can continue without logging in. If the name of this app didn’t already give you a hint, Airy is known for being a reliable, lightweight software for converting MP4 to MP3.