Cloud Invent now offers Cheetah Solver SDK for anybody interested in constrained geometric modeling.
This SDK contains the same DLLs that we use in our Cheetah Solver Plugin for AutoCAD.
However this SDK is not finished yet. We present just a preliminary version of .NET API. This beta version of Cheetah Solver API is free. You can download it from NuGet.
Documentation for Cheetah API is not ready yet. The preliminary version of documentation will be published soon. Meanwhile you can use some examples submitted on GitHub.