With competition growing in the streaming music market, Spotify announced a series of changes meant to entice new customers and extend its digital footprint farther around the world.

At a news conference in Manhattan that was broadcast online, Daniel Ek, the company’s co-founder and chief executive, said the company was increasing the amount of free music it makes available on mobile devices, opening in 20 emerging markets and adding the music of Led Zeppelin.

Spotify has fascinated those in the tech world practically since it began in Sweden in 2008, both for its sleek design and ambitious business model. Positioning itself as a legal alternative to piracy, the service makes music available free with advertising, or for monthly subscriptions of about $5 to $10, which eliminate the ads and add perks like access through mobile devices. Still, the relative lack of free music available on mobile phones has been seen as an impediment to Spotify’s growth.

“The world has changed a lot since we launched,” Mr. Ek said in an interview after the news conference. “More than half of all users are now signing up straight to mobile, and there is a huge correlation between playing on mobile and getting people to convert.”