Streaming music service Deezer is going head to head with Spotify in the apps-platform stakes, launching its Open Deezer initiative. It’s an API for developers to create applications that tap into Deezer’s catalogue of music and user data, through SDKs for Android, iOS and web applications. Partners including Facebook, Twitter, Last.fm, Orange, T-Mobile, Sonos and Nissan have already been given access to the API, and the company is holding Deezer Hackathon events in Paris and Berlin in the coming weeks to get developers on board. Here’s the key point though: developers creating Deezer-powered apps will get a £9.99 payment for every new subscriber that signs up through those applications. That, along with Deezer’s web-based platform, provides sufficient differentiation to Spotify to make the battle for developers very interesting.