Opossum offers some of the best performing optimization algorithms in Grasshopper: model-based RBFOpt and RBFMOpt and evolutionary CMA-ES and NSGA-II.

Series of algorithms for: a) Graphs b) Aggregations c) Iso Meshes

Clipper is a 2D polygon Clipper offering polygon boolean operations (clipping): Intersection, Join, Difference, and robust polygon offsets.

Volumetric Modeling with signed distance functions (SDF) for Grasshopper.

Leopard is an open source mesh processing solution for grasshopper.

Culebra.NET is a 2D|3D Multi Object Behavior library written in C# (Wrapper around Culebra Java library) focused on hybrid system interactions.

Bison is a landcape architecture plugin for Grasshopper + Rhino 6. It features tools for terrain mesh creation, analysis, editing, and annotation.

VisualARQ adds flexible BIM features to Rhino, and speeds up the process of modeling an architectural project in 2D and 3D.