SU2 is an open-source collection of software tools written in C++ and Python for the analysis of partial differential equations (PDEs) and PDE-constrained optimization problems on unstructured meshes with state-of-the-art numerical methods. SU2 is a leading technology for adjoint-based optimization. Through the initiative of users and developers around the world, SU2 is now a well established tool in the computational sciences with wide applicability to aeronautical, automotive, naval, and renewable energy industries, to name a few.