Sources speaking to TechCrunch claim that Spotify is launching a browser-based app for its popular music service, following services like Last.fm. The browser versions seems like an alternative to the free app, though this is not confirmed. Logging into a Spotify account on a computer accesses the service. TechCrunch did not see it in action, so judgements on performance are out. 

It is not clear whether the browser app is going to be free. Users have to pay a subscription fee to download the mobile app, though they can use the Radio feature for free. The free service now limits the music users can listen to and the amount of times a certain song is playable. Users need to buy the song from Spotify, or a competitor like iTunes, for unlimited listening.  The free app for the music service uses frequently ads that interrupt listening; Spotify offers ad-free listening for $4.99 a month. 

A new subscription service may be introduced at around $8 a month, offering ad-free services and the mobile app. 

TechCrunch speculates hat Spotify could offer users a subscription service not tied to the mobile app; not all users will use the mobile app, so offering it as an optional upgrade may make sense. 

Discovery for subscribing to playlists is going to be "rewired" according to TechCrunch's sources. Users can subscribe to a playlist to receive updates when new music is added, and Spotify apparently wants to encourage more users to subscribe to playlists.

"[B]ig name celebrities, musicians, and DJs [may be recruited] to share playlists," and the service suggests who users should follow via recommendations. 

Spotify is available to download now for PC and Mac; mobile apps are available for iOS, Android, Windows Phone, and BlackBerry devices if subscribed to Spotify.