Spotify has become the first music streaming service to pass 50 million paying customers, according to BBC.
It reached the milestone after adding 10 million subscribers in less than six months, staying ahead of its closest rival, Apple Music.
But Spotify - which costs £10 a month in the UK - faces competition from deep-pocketed tech giants Amazon and Google, as well as Apple.
It is also yet to reach a new licensing deal with record labels, analysts say.
Mark Mulligan, a music industry analyst at Midia Research, said: "Spotify is the standout success for streaming music globally - no one else comes close in terms of paid subscribers."
Apple Music had about 20 million subscribers by December 2016, 18 months after launching.