The platform, owned by the creators of Skype, grants subscribers unlimited, ad-free access to millions of tracks via PC, tablets and smartphones.
Free users are granted access to a finite amount of music each month, which is also uninterrupted by advertisements. A gauge helps customers keep track of how much free playtime they have left.
Two premium packages are on offer. For £4.99 a month, users can access unlimited music through the desktop and browser services, and for £10 a month they can take advantage of the iOS and Android apps.
Spotify, which launched its official iPad application yesterday, offers subscriptions at the same cost, but does not support browser-based playback.
Rdio is available online now, and its accompanying apps can be downloaded via Google Play and the App Store.
> Spotify to launch online radio app to rival Pandora, says report