The Spotify Echo Nest Objective-C library access the music functionalities of the API with Apple development in mind. Resources include full access to artists, songs, playlists, and taste profiles methods. It also provides methods to retrieve information of a particular track. An example app is available to demonstrate how to integrate the library into an XCode project.
The InternetDJ API opens this electronic music site to your app. Since 1997 (not a typo!) composers and fans have been able to share and mix music and videos. According to the API's website, requests are limited to 5,000 a day, responses are in JSON and an auth key is required.
BandPage creates a platform where musicians, fans and others in the music industry can interact easily. For musicians, it can be difficult to stay connected to fans who are scattered all over the web. BandPage aims to rectify this issue by providing musicians with a one-stop-shop solution; update once and publish everywhere. Bands simply create a BandPage profile and all their info is updated across various other online channels as well. The BandPage API allows third party developers to access this data and integrate it into other applications.