I'm a mechanical engineer but write code ~50% of my time. My main contribution: CPL library (www.cpl-library.org), links software on high-performance platforms, open-source with cross-language bindings and continuous-integrated testing. We have PhD students using CPL library at other universities and recently I contributed to a successful eCSE grant, funding me to apply CPL library to granular flows. My experience started in FORTRAN, heavily optimised and parallelised (MPI). With new user/developers of my code, I started a repository, realising the importance of sustainable software. I refactored to modern Fortran, developed a python framework to run and snapshot code for reproducibility.