Cool Document Viewer available in the Android 4.4(KitKat)

Dear Team,

Is there Proprietary Document Viewer available within Android 4.4(KitKat) ? if yes let me know in detail.

Possibility of integrating new document viewer within Application SandBox on Android 4.4,

Basically i am looking for Document viewer APIs to open documents within the application.

Thanks & Regards
Rajesh. S