Microsoft has released a standalone client for Lync 2013, similar to Lync 2010. But the client is basic in the feature set as the name suggests.
The full Lync 2013 client comes bundled with the Office 2013 suite. The standalone Lync 2013 Basic client gives IM, audio & video calls, online meetings, availability (presence) information and sharing capabilities. It’s a slimmer version of the full Lync 2013 client and provides the same core functionality.