Visits to music streaming service Spotify.com have more than doubled in February, according to internet monitoring company Hitwise.
The site registered its one millionth user, of which 250,000 are in the UK, having launched just four months ago.
Visits by UK users rose by 250% in the four weeks ending while searches for 'spotify' increased 400% during the same period.
Spotify is able to offer both legal and free music as music artists are paid royalties for the music you choose to listen to.
There's a wide range of music available, despite the site recently being forced to remove certain music from its database due to licensing issues with some artists and record labels.
It is also attracting interest from advertisers and has signed up brands including Xbox, T-Mobile and Vodafone.
Record labels which have signed u include Warner Music, Universal and EMI.
Hitwise reported that the type of people most likely to visit Spotify are: 'young, single and mostly well-educated people who are cosmopolitan in tastes and liberal in attitudes.’
The site works by streaming music to your computer over a broadband internet connection, so, unlike iTunes and similar music download services, no music files are downloaded to or stored on your computer.
Previously the site worked on an invitation-only basis to encourage slow but stable development of the Spotify service.