Other Tracking Client APIs can be found on the Tracking Server Resource Center
The Tracking Client API for .Net is available for Microsoft .Net Framework 4.0 as well as .Net Framework 3.5, and works alongdise with the ArcGIS Runtime SDK for WPF, and the ArcGIS API for WPF.
To download the Tracking Client SDK for .Net, which includes the API Library, documentation, and samples, simply (1) login and (2) download the Tracking Client SDK for .Net.