Android M SDK available for Developers.

Android Marshmallow codename Android M version 6.0 SDK is available for Developers to update their apps and make it compatible.

Nexus 5,6,9 and Player is in testing with Android M.

Hopefully in early November it will be in market.

Explore what's new —runtime permissions, Doze and App Standby power-saving features, new assist technology, and more.

So developers get yourself ready for next Android.

Get all tools and details  at http://developer.android.com/preview/index.html