RDKit
RDKit is a collection of cheminformatics and machine-learning software written in C++ and Python. It includes BSD license - a business friendly license for open source, Core data structures and algorithms in C++, Python 3.x wrapper generated using Boost.Python, Java and C# wrappers generated with SWIG, 2D and 3D molecular operations, Descriptor and Fingerprint generation for machine learning, Molecular database cartridge for PostgreSQL supporting substructure and similarity searches as well as many descriptor calculators, Cheminformatics nodes for KNIME, and Contrib folder with useful community-contributed software harnessing the power of the RDKit.