This is mostly for my own usage. I have a strong preference for wiring and testing on bread boards before I order PCB’s. Sometimes it saves you 2-3 extra rounds to be able to do simple concept testing. I have plenty of breakout boards with STM32, but I fancied my own with my own SWD connector etc. For now I am using the first GPIO Hat’s for Zero more on breadboards they are not designed for than on the Zero. It only have components on one side using a two layer PCB, so this is designed to be cheap.
This breakout will work for STM32F103Rx, STM32F105Rx, STM32F107Rx and STM32F405Rx. It might work for others as well, but I have not checked yet.