G+Smo (pronounced gismo or gizmo) is a C++ library for isogeometric analysis or IGA, developed at RICAM, Linz. It implements mathematical tools for geometric design and numerical simulation. Geometry plus simulation modules was envisaged by Angelos Mantzaflaris in 2012 and aims at the seamless integration of Computer-aided Design (CAD) and Finite Element Analysis (FEA).