Open Connectivity Foundation's (OCF) Open Inter-Conneect (OIC) for .Net providing device discovery, arbitrary transport, client/server communication.
More details about OIC here: https://openconnectivity.org/
Emitter is an MQTT client tailored for emitter.io service, allowing real-time publish subscribe. It supports full .Net Framework, .Net Micro Framework and WinRT platform (Windows 8+ and Windows Phone 8+).
Enhanced CSharp bindings for the Tinkerforge range of Bricks and Bricklets.
This set of bindings includes three improvements over the standard library. Full Async / Await pattern support, Value Tuple returns and full support for Reactive Extensions