Pandora said Thursday that it has surpassed 250 million registered users, who have created more than six billion stations on its Web-based radio service.

The company crossed the 200 million mark in April 2013. Pandora's first 100 million users took six years to generate; the next 100 million took two years.

The latest milestone indicates its growth, roughly 50 million registered users a year, has held up even as upstart rivals arise and tech giants introduce competitors. Pandora has prided itself in continuing to grow and lead the market by number of listeners, while giants like Apple and Google added new services like iTunes Radio and All Access last year and new smaller startups like Spotify offered up new listening options and marketing machines like Beats Music emerged.

Pandora released news of milestone alongside the lineup of music acts its set up at the South by Southwest festival in Austin. The performances will be streamed live on Pandora.