Today, Rdio launched an iPad app, becoming the second of the larger music streaming services to do so, after Slacker Radio. The Rdio app is now universal and works on the iPhone/iPod touch and iPad.

First introduced in 2010, Rdio offers ad-free music for as little as $4.99 per month. It competes directly with Slacker, MOG, and Spotify, among others, which offer streaming music services for computers and devices.

Unlike Spotify, Rdio doesn’t offer a free listening plan. However, it does allow new users to try out the service for free for seven days. To do so, just sign up using your email address within the app.  Best of all, a credit card is not necessary during the promotion.

Rdio for iPad

Rdio for iPad

For those seven days, you’ll receive access to the company’s $9.99 plan. This offers customers unlimited web and mobile access and the ability to sync your music to your iPhone or iPad for offline listening.

App features includes:

  • See your network’s activity
  • Enjoy offline access to music
  • View user profiles
  • Check out top charts, heavy rotation and new releases
  • Listen to Artist Radio and find Recommendations
  • Collaborate on Playlists
  • Find and follow friends

Rdio, which was original developed by the founders of Skype, offers access to 7 million song titles. This compares to MOG’s 11 million and Spotify’s 13+ million.

We recommend trying out the service on your iPad and seeing what you think. The universal Rdio app is available today in the App Store.

[Updated to reflect choice of Slacker Radio]