axle OS is a hobby microkernel and userspace. I started the project in early 2016, and have had stints of working on it heavily since then. axle OS’s first incarnation was a multitasking monolithic kernel, with little support for IPC, user-mode or process loading. The current incarnation is a microkernel built around variable-length IPC messaging. All applications, including the desktop environment and device drivers, are ELF executables running in userspace.