openbabel  3.1.1
About: Open Babel is a chemical toolbox designed to speak the many languages of chemical data. It’s an open, collaborative project allowing anyone to search, convert, analyze, or store data from molecular modeling, chemistry, solid-state materials, biochemistry, or related areas.
  Fossies Dox: openbabel-3.1.1-source.tar.bz2  ("unofficial" and yet experimental doxygen-generated source code documentation)  

What's New in Version 2.3

Throughout the API documentation, new classes and methods are indicated with a disclaimer "Since: version 2.3."

Several new classes and features have been introduced, notably

In addition, a wide variety of new plugins are available, including