The number of Spotify apps jumped from 10 to 22 yesterday, with the launch of the company’s second wave of apps. There are more partnerships with big names music brands, as there was in the first ten apps. But there are also some playful apps created by third party developers (sort of) which show the direction that Spotify is headed in trying to expand into a full fledged music platform. Below is a nice summary from Ellis Hamburger:

  • Classify: classical music organized by genre, instrument, mood, composer, and more
  • The Complete Collection: 150 album booklets available, with details about who wrote and produced your favorite pop songs
  • Def Jam: 26 years of Dem Jam recordings and information in one app
  • Digster: match Digster playlists to your listening history and Facebook likes, then turn on full screen mode for partying
  • Domino: highlights artists throughout Domino’s storied history
  • Filtr: builds playlists based on the tastes of your Facebook friends
  • Hot or Not: decide which of two songs is hot or not, then ascend the rankings as you mark more songs correctly
  • The Legacy Of: a “visual feast” containing history’s most acclaimed musicians
  • Matador Records: an interactive guide to the New York music label, including all of its albums and music
  • [PIAS]: experience new albums and curated playlists from the indie label
  • TweetVine: born from a London hackathon, TweetVine scans Twitter for #NowPlaying hashtags to show you what people you’re not friends with are listening to
  • The Warner Sound: the complete Warner music experience, which includes Green Day, Cee Lo Green, Wiz Khalifa, and Fun

The apps from Matador and Domino work much like the earlier creations from Rolling Stone and Pitchfork, curated music except instead of a magazine, it’s a label that is doing the selecting.

TweetVine is a third party app created by Matt Larsen and Matt Schofield (ok technically these guys work at Universal Music), two U.K. music developers who were at Spotify’s recent hackathon in New York, and this is where things get interesting. The app is a discovery tool based on what’s trending, helping Spotify users expand beyond the limited social graph of Facebook that now makes up Spotify’s only social integration. Larsen has a very detailed blog post up on what it’s like working with the Spotify API that all aspiring music developers should check out.

The Spotify platform still isn’t as open to third party work as Facebook, iOS or Android. But this new class of apps show a lot more of the playful indy spirit, with apps like Hot or Not encouraging users to engage with the music. We’ve heard that Spotify is hoping to open up to third party developers within the month, so check back for details. The big thing holding Spotify back now is that none of the apps are available on mobile, where it’s seeing its biggest growth in usage.