Spotify continues its dominant lead in the music-streaming space, with the Stockholm-based company announcing that it is now serving 6 million paying subscribers with tunes. 

Beyond the 6 million paying subscribers - who have brought in more than $500 million in revenue for the company - Spotify is also serving 24 million active users across 20 countries. Spotify makes revenue off the free-users, thanks to a bevy of ads that are played in between a certain number of songs. 

In recent weeks Spotify has continued to cater for its users with a continued push for its new web-based music player and a social revamp for its desktop application. 

Spotify has been available since 2008, but hit its focal point when it launched in the US in the summer of 2011. The US launch brought not only a large number of new users, but a also partnership with Facebook that we imagine brought in a big chunk of the 24 million active users. 

Spotify's worldwide strength may be tested soon. Apple and Google noted.