As part of my research, or for fun, I write a lot of software.
I've been the maintainer and primary developer for CrystalExplorer since ca. 2016. It's a pretty popular program, used by thousands of people all across the globe.
My own python (cython & C) library for various utility things including Hirshfeld surfaces, spherical harmonic shape descriptors, elastic tensors, general manipulation of crystals and molecules and much more!
I made a quick and dirty binary file format for interoperating between C, fortran, C++ and python. The implementation (and probably the design) could do with some work, but it's been used for a while in CrystalExplorer and makes my life easier from time to time!
This one is mostly not me, but I made a lot of contributions to tonto during my PhD. Things have slowed down a bit in the meantime, but since I rewrote the build system and migrated the codebase to git & made the tests run in an acceptable amount of time among other things I take some of the blame for the program.