Integrated Application and Lync Integration for SharePoint - Lync API 2013

I have an application hosted on SharePoint and you need to integrate Lync features into it. I assume that the Lync client is not installed on the target machine. Lync features should work for both On-Premise and Lync online.

I have seen UCWA 4.0, but this does not work with applications hosted on SharePoint and office applications 365.

Is there any other API I can use?