QuickFIX/n is a .NET port of QuickFIX, an open source C++ FIX engine.
We love QuickFIX. We have been contributors nearly since its conception and use it heavily in our products and consulting.
The goal of QuickFIX/n is to create an open source FIX engine that feels native to C#. The (C++) QuickFIX project maintains a C# wrapper which has been used successfully in .NET for many years, but it results in code that is not idiomatic of .NET development. QuickFIX/n attempts to keep the same robustness and conformance of QuickFIX with a similar API while bringing native performance and idiomatic usage to .NET.
For Java development, please visit the excellent QuickFIX/J.
QuickFIX/n uses the QuickFIX name with the full backing and support of QuickFIX and its creator Oren Miller.