, the music-based social network now owned by CBS, has finalized licensing agreements with all four major record labels, as well as a number of independents labels and their aggregators.

The service now allows free, on-demand streaming of up to 3.5 million tracks, but according to CBS will soon expand well beyond that. "The mission is to have every track available," said co-founder Martin Stiksel at a press conference today in the CBS building in New York where the announcement was made.

In addition to the label deals, the company also introduced an "Artist Royalty" program for independent artists. These artists can upload their music directly to, and receive payment for each stream.

The revamped service is designed primarily as a free music discovery tool. It is a mix of free, ad-supported streams and links to purchase the song from existing digital retailers like iTunes and Amazon, as a sort of "try before you buy" format. Users get three free streams, after which they're prompted to buy the track.

The service also recommends similar music, allows users to create customized Internet radio stations, and requires no software download and no login.

Ads will be small, short video commercials that run alongside the music, and can be targeted based on users demographic information.

The new launches today in the U.S., the UK and Germany with further global expansion planned. to date has compiled some 20 million unique monthly listeners across 240 countries. CBS bought the company last May for $280 million.