Digital music streaming and social discovery website Rdio announced today that it has partnered with distributors CD Baby and Tunecore, increasing the site's play-on-demand track catalog to more than 18 million.

The catalog expansion puts Rdio just above Spotify in terms of total tracks claimed, according to Tech Crunch.

More than 250,000 artists were added to the service with the partnership.

“We are excited to partner with TuneCore and CD Baby, two of the best distribution tools out there for independent artists,” said Drew Larner, CEO of Rdio. “Independent music is a vital part of Rdio’s catalog. We're glad to support hundreds of thousands of self-released artists by connecting their work to new music fans from all over the world.”